Lengthen Command - AutoCAD

1. What should the drafter expect from that selection?
   Answer: AutoCAD reports the line's current length and leaves the line unchanged. When working with LENGTHEN, it helps to understand that the command has two distinct phases: first it informs, then it modifies. AutoCAD is designed so that selecting an object at the initial prompt — before you've specified a method like Delta, Percent, Total, or Dynamic — simply reports that object's current length. This is a deliberate "look before you touch" safeguard built into the command. That's exactly why C is correct. Clicking the line at the opening prompt triggers a read-only response: AutoCAD displays the current length (and included angle, for arcs) in the command line and then re-issues the prompt. The line itself is untouched. You're essentially asking AutoCAD, "How long is this?" before deciding how to change it. A describes behavior that doesn't exist in LENGTHEN — the command has no memory of a "most recent length change" that it automatically repeats on a new selection. B confuses the initial selection with the Dynamic sub-option, which only activates when you explicitly type DY at the prompt; simply clicking the object never drops you into dynamic dragging mode. D is a plausible-sounding trap because the Properties palette does show length, but LENGTHEN never opens Properties — it's a standalone editing command, not a palette trigger. A good study habit here: whenever a command asks you to select an object before you've configured how to act on it, AutoCAD is almost always gathering information, not making a change. Remember — inform first, modify second.
2. Which LENGTHEN workflow is the most efficient?
   Answer: Choose Dynamic, select the line near the movable endpoint, and drag it to the target point using an object snap. When a LENGTHEN question involves dragging to a known geometric point rather than a known numeric value, think about which option lets AutoCAD measure for you instead of making you measure first. The Dynamic option does exactly that. You activate it, click the line near the endpoint you want to move, and then drag that endpoint to any snappable point in the drawing — AutoCAD updates the length in real time. Because the target point is reachable with an object snap, you never need to calculate or measure anything; the geometry does the work. That's why D is the most efficient workflow here. The other options all force unnecessary manual measurement. A requires you to know both the current length and the target length so you can compute a percentage — two measurements plus arithmetic just to avoid one snap. B, the Total option, demands that you measure the final desired length and type it in; the scenario explicitly states that length hasn't been measured, so this is a dead end. C, Delta, asks for the change in length from the current endpoint to the target, which still requires you to measure a distance — a step the Dynamic mode eliminates entirely. All three of these workflows treat the problem as a numeric input task when it's actually a point-picking task. The exam strategy here: whenever a problem says the target location is geometrically defined (an existing point, intersection, endpoint, etc.) but no numeric length is given, Dynamic is almost always the right LENGTHEN choice because it lets object snaps replace manual calculation entirely.
3. Which LENGTHEN sequence sets the required final angle directly?
   Answer: Choose Total, choose Angle, enter $135^\circ$, and select the endpoint to move. When working with the LENGTHEN command on arcs, the key distinction is between how much to change versus what the final value should be. AutoCAD's LENGTHEN offers several modes, and choosing the right one depends on whether you're specifying a change or an absolute result. The Total option sets the arc's included angle to an exact final value — precisely what the problem demands. Since you want the arc to end at exactly $135^\circ$ regardless of where it starts, you choose Total, then select the Angle suboption (because you're working with angular length, not linear length), enter $135$, and click the endpoint you want to move. AutoCAD recalculates and places that endpoint so the arc spans exactly $135^\circ$. That makes B the correct sequence. A is wrong because Delta adds or subtracts a change from the current value. To use Delta correctly here, you'd enter $60^\circ$ (the difference between $135^\circ$ and $75^\circ$), not $135^\circ$. Entering $135^\circ$ in Delta mode would overshoot to $210^\circ$. C is wrong because Percent scales the arc relative to its current length — $135\%$ of $75^\circ$ yields approximately $101.25^\circ$, not $135^\circ$. To reach $135^\circ$ with Percent, you'd need $180\%$. D is wrong because omitting the Angle suboption under Total causes AutoCAD to interpret your input as a linear length in drawing units, not an angular measure, producing an incorrect result. Study tip: On AutoCAD questions about LENGTHEN, always ask yourself two things: Is the value a final target (Total) or a change (Delta)? And is the measurement angular or linear? Both sub-decisions must match the problem.
4. Which LENGTHEN workflow makes the required change without first calculating a new endpoint coordinate?
   Answer: Choose Delta, enter $1.75$, and select the line near its right endpoint. When working with AutoCAD's LENGTHEN command, the key decision is choosing between Delta and Total mode, and understanding what value each one expects. Delta mode adds (or subtracts) an amount relative to the current length. Since the line needs to grow from $7.35$ to $9.10$ units, the required change is $9.10 - 7.35 = 1.75$ units. Entering $+1.75$ in Delta mode and clicking near the right endpoint tells AutoCAD to extend that end by exactly $1.75$ units along the existing direction — no coordinate math required. That's option A, which is correct. B is wrong because entering $-1.75$ in Delta mode shortens the line by $1.75$ units, bringing it to $5.60$ units — the opposite of what's needed. The negative sign reverses the direction of change. C is wrong because Total mode expects the final desired length, not the change amount. Entering $1.75$ in Total mode would shrink the line to $1.75$ units, not extend it to $9.10$. D is wrong for two reasons: while entering $9.10$ in Total mode is numerically correct, selecting the line near its left endpoint would move the left endpoint instead of the right one — violating the requirement that the left endpoint stay fixed. A quick memory aid: Delta = difference, Total = target. Also remember that LENGTHEN always moves the endpoint closest to where you click, so endpoint selection is just as important as the value you enter.
5. Which use of LENGTHEN most directly satisfies the requirement?
   Answer: Choose Total, enter $12$, and select the arc near the endpoint that may move. When working with LENGTHEN in AutoCAD, the key is matching the option's behavior to the requirement's units. The question gives you a target in linear units ($12$ units of arc length), so you need an option that accepts a direct length value — not a percentage, not an angle. The Total option sets the object's new total length to whatever value you enter. Since you want an arc length of exactly $12$ units, choosing Total, entering $12$, and selecting near the movable endpoint accomplishes this in one step. AutoCAD stretches or trims that endpoint until the arc measures $12$ units — radius unchanged, endpoint repositioned along the circle. That makes A the most direct solution. B is wrong because Delta adds or subtracts a value relative to the current length. If the arc is already, say, $14$ units long, entering $12$ would produce an $26$-unit arc, not a $12$-unit one. You'd need to calculate the difference first, which adds steps and room for error. C uses Total → Angle, which sets the arc's included angle to $12°$. While an angle does indirectly define arc length ($L = r\theta$), the requirement is stated in linear units. This option forces you to convert, and $12°$ on an $8$-unit radius gives approximately $1.68$ units — nowhere near $12$. D uses Percent, which scales the arc to $12\%$ of its current length — again requiring you to know the current length and do extra math. The strategy to remember: when a question says "final length of exactly X units," always reach for Total in LENGTHEN. Reserve Delta for incremental changes and Percent for proportional scaling.
6. What are the final lengths of the two lines?
   Answer: They become $50$ units and $75$ units, respectively. When you see a question about LENGTHEN with the Percent option, remember one key rule: the percentage you enter applies proportionally to each selected object's current length — it does not set a fixed absolute length. A value below $100\%$ shortens the object; above $100\%$ lengthens it. Here, entering $62.5\%$ means each line is scaled to $62.5\%$ of its original length. For the $80$-unit line: $80 \times 0.625 = 50$ units. For the $120$-unit line: $120 \times 0.625 = 75$ units. That confirms A as the correct answer — the lines become $50$ and $75$ units, respectively. Choice B is a classic trap: it treats the percentage as an absolute target length, as if both lines are simply set to $62.5$ units. That's not how Percent mode works. Choice C reflects a subtraction mistake — perhaps subtracting $62.5$ from each original length ($80 - 62.5 \approx 30$... loosely) rather than multiplying by the percentage. Choice D goes in the opposite direction entirely, suggesting the lines grew, which would only happen if the entered percentage exceeded $100\%$. A helpful way to remember this: think of LENGTHEN Percent like a scaling factor. $62.5\% = 0.625$, and you multiply — never subtract, never treat it as absolute. When studying AutoCAD modify commands, always clarify what the input value represents (absolute length vs. percentage vs. delta) for each sub-option, since mixing these up is the most common source of errors on exam questions like this.
7. Approximately what is the arc's new included angle?
   Answer: $82.9^\circ$, because the length increment corresponds to about $22.9^\circ$. Whenever you see a LENGTHEN Delta question involving an arc, remember that entering a plain length value (without the Angle suboption) always adds or subtracts arc length in drawing units — never degrees directly. To find the new angle, start from first principles. The original arc length is calculated with $L = r\theta$, where $\theta$ is in radians. For a $5$-unit radius and $60^\circ$ included angle: $\theta = 60 \times \frac{\pi}{180} \approx 1.0472 \text{ rad}$, so $L = 5 \times 1.0472 \approx 5.236$ units. Adding the $2$-unit delta gives a new arc length of $7.236$ units. Converting back: $\theta_{new} = \frac{7.236}{5} \approx 1.4472 \text{ rad} \approx 82.9^\circ$. That confirms C is correct — the increment of $2$ units corresponds to an angular increase of about $22.9^\circ$. A is wrong because AutoCAD never interprets a plain numeric entry in LENGTHEN Delta as degrees; that would require the Angle suboption. B confuses the formula by dividing by the diameter ($10$) instead of the radius ($5$): $2/10 = 0.2 \text{ rad} \approx 11.5^\circ$, producing $71.5^\circ$ — a classic off-by-two error on the radius/diameter distinction. D has no geometric basis; a positive delta shifts the endpoint by a fixed length, not a proportional multiplier. Your key study tip: always distinguish between LENGTHEN Delta's default (linear units) and its Angle suboption (degrees). Mixing them up is the most common trap on arc-editing questions.
8. Which statement correctly describes the result?
   Answer: Both lines become $25$ units long; the first extends by $7$ and the second shortens by $6$. When you see a question involving LENGTHEN with the Total option, the key concept to hold onto is that Total sets an absolute final length — it is not an incremental change. Whatever value you enter becomes the new length of the selected object, regardless of whether that means extending or shortening it. Here, you enter $25$ as the total length and select each line near its right endpoint (which tells AutoCAD which end to move). The $18$-unit line is shorter than $25$, so AutoCAD extends its right end by $7$ units, making it exactly $25$ units. The $31$-unit line is longer than $25$, so AutoCAD shortens its right end by $6$ units, also making it exactly $25$ units. Both lines end up $25$ units long — confirming D is correct. A is wrong because it invents a restriction that doesn't exist. The LENGTHEN Total option absolutely can shorten an object; there is no minimum-length rule blocking it. B describes the LENGTHEN Delta behavior — adding a fixed increment — not Total. If you used Delta with $25$, the results would be $43$ and $56$, but that's the wrong command option entirely. C is another Delta-style trap: adding $7$ to both lines implies an incremental operation, and the resulting lengths don't match what either option would actually produce. A reliable memory anchor: think of Total as "total makeover" — the number you type is the final length, full stop. Delta adds or subtracts; Total replaces.
9. Why does this workflow not produce the requested perimeter?
   Answer: LENGTHEN does not modify closed objects, so the closed polyline remains unchanged regardless of the entered value. Whenever you see a question about LENGTHEN on the AutoCAD exam, the first thing to recall is the command's fundamental limitation: it cannot operate on closed objects at all. This single rule unlocks the entire question. LENGTHEN is designed to extend or shorten open objects — lines, open polylines, arcs, and similar geometry. When you select a closed polyline, AutoCAD simply ignores the operation. It doesn't matter which option you use (Total, Delta, Percent, or Dynamic) or what value you enter — the closed polyline remains completely unchanged. That's exactly what happens in the scenario: the designer's workflow fails not because of a wrong value, but because the target object is closed. Answer B correctly identifies this root cause. Looking at the distractors: A is wrong because LENGTHEN can modify open polyline segments individually — the restriction is specifically about closed objects, not polylines in general. C is wrong on two levels: first, LENGTHEN Total sets the absolute final length of the selected segment (so $52$ would be a valid entry for a longer segment), and second, even a perfectly valid entry won't matter since the closed polyline blocks the command entirely. D is wrong because it describes a plausible misunderstanding of how Total works, but the real issue isn't about unaffected segments — the command doesn't execute at all on a closed object. As a study tip, remember this pairing: LENGTHEN = open objects only; PEDIT or STRETCH are your tools when you need to modify closed polyline geometry. Closed-object restrictions are a favorite exam trap.
10. After choosing Delta, entering $-6$, and selecting near the endpoint at $x=10$, what is the resulting line?
    Answer: Its endpoints are $x=16$ and $x=34$, giving a length of $18$ units. When using LENGTHEN with the Delta option, the key concept to understand is that AutoCAD modifies whichever end of the line you click near — it does not move the opposite endpoint. The delta value you enter is added (or subtracted) from that selected end. A negative delta shortens the line from the clicked end. Here, the original line runs from $x=10$ to $x=34$, giving a length of $24$ units. You enter $-6$ and click near the endpoint at $x=10$. AutoCAD shortens the line from that end by 6 units, moving it inward (toward $x=34$): $10 + 6 = 16$. The fixed end at $x=34$ stays put. The result is a line from $x=16$ to $x=34$, with length $34 - 16 = 18$ units — confirming answer B. A is wrong because it places the new endpoint at $x=4$, which would mean the line was extended outward (away from $x=34$) by 6 units, not shortened inward. That would require a delta of $+6$ on that end, not $-6$. C is wrong because it moves the wrong endpoint — it shifts $x=34$ to $x=28$, as if you had clicked near the right end instead of the left. The endpoint you click is the one that changes. D is wrong because $x=6$ reflects a $-4$ shift from $x=10$, not $-6$ — likely a simple arithmetic error. The golden rule: whichever end you click, that's the end that moves. Always confirm which endpoint you're selecting before executing LENGTHEN.

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