PSAT Math : How to find the length of a side of a polygon

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Find The Length Of A Side Of A Polygon

If the following shape was going to be drawn in a circle, what is the minimum radius of the circle?

Possible Answers:

10

11

7

9

8

Sat_math_picture3


Correct answer:

7

Explanation:

IF you draw the longest diagonal across the shape, the length of it is 13.4. This means the radius must be at least 6.7. The answer is 7.

Example Question #2 : How To Find The Length Of A Side Of A Polygon

Heptagon

Note: Figure NOT drawn to scale.

The above polygon has perimeter 190. Evaluate .

Possible Answers:

Correct answer:

Explanation:

To get the expression equivalent to the perimeter, add the lengths of the sides:

Since the perimeter is 190, we can simplify this to

and solve as follows:

Example Question #3 : How To Find The Length Of A Side Of A Polygon

Heptagon

Note: Figure NOT drawn to scale.

The perimeter of the above polygon is 225. Also, .

Evaluate .

Possible Answers:

Insufficient information exists to answer the question.

Correct answer:

Explanation:

To get the expression equivalent to the perimeter, add the lengths of the sides:

Since the perimeter is 225, we can simplify this to

and, furthermore, since ,

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