SSAT Middle Level Math : How to find a triangle on a coordinate plane

Study concepts, example questions & explanations for SSAT Middle Level Math

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Example Questions

Example Question #8 : Coordinate Geometry

Triangle2

Find the area of the above triangle, given that it has a height of 12 and a base of 10. 

Possible Answers:

Correct answer:

Explanation:

Because this is a right triangle, the area formula is simply:

 

 

Thus, the solution is:

Example Question #9 : Coordinate Geometry

Triangle6

Given the above triangle is an equilateral triangle, find the perimeter in units as drawn in the coordinate system.

Possible Answers:

Correct answer:

Explanation:

Using the coordinate system, one can see the base of the triangle is 6 units in length. Since it is an equilateral triangle, the other two sides must also be 6 units each in length. Therefore the perimeter is:

Example Question #1 : How To Find A Triangle On A Coordinate Plane

Triangle6

The isosceles triangle shown above has a perimeter of 22 and base of 6. Find the lengths of the left and right sides, respectively. Assume no other side has a length of 6.

Possible Answers:

Correct answer:

Explanation:

With a perimeter of 22 and base of 6, this means the other two sides must add up to: 

Because an isosceles triangle must have two sides equal in length and we know from the problem that no other side equals 6, the two remaining sides must be equal to each other.

 

Thus, to be equal to each other and also add up to 16, each side must be 8 units in length.

Example Question #2 : How To Find A Triangle On A Coordinate Plane

Triangle2

Given the above triangle has a base of 5 and height of 6, what is the perimeter of the triangle?

Possible Answers:

Correct answer:

Explanation:

First, use the Pythagorean Theorem to find the length of the hypotenuse:

 where  and  are 5 and 6, respectively, and  is the hypotenuse.

Thus, 

 

Finally, the perimeter is the sum of the sides of the triangle or:

Example Question #3 : How To Find A Triangle On A Coordinate Plane

Triangle4

Given triangle , where  is at point  and  is at point , find the area.

Possible Answers:

Correct answer:

Explanation:

To find the area of this triangle, we first need to determine the length of sides AB and BC. First, point B shares the same x-coordinate as point A and the same y-coordinate as point C. Thus, B must be located at point (-2,-2). 

The length of side AB must then be:

  

and the length of side BC:

 

 

Using the area formula,

we can find the area using the base (side BC) and height (side AB):

Example Question #4 : How To Find A Triangle On A Coordinate Plane

Triangle4

Given triangle , where side  and side , find the perimeter.

Possible Answers:

Correct answer:

Explanation:

Use the Pythagorean Theorem to find the length of side AC:

 

Then, the perimeter is simply the sum of all three sides:

Example Question #5 : How To Find A Triangle On A Coordinate Plane

Triangle6

The above triangle has base 6 and height 4. Find the perimeter.

Possible Answers:

Correct answer:

Explanation:

Because the y-axis bisects the base, we can divide the triangle into two, equal right triangles. The base of the right triangle is thus half that of the larger triangle, or 3. The height is still 4. To find the hypotenuse, use the Pythagorean Theorem:

 

 

Thus, we now know the base as given in the problem and each of the other two sides (which are also the hypotenuses of the right triangles).

Therefore, the perimeter is:

Example Question #6 : How To Find A Triangle On A Coordinate Plane

Triangle6

Given a height of  units and base of  units, find the area of the triangle shown above.

Possible Answers:

Correct answer:

Explanation:

The area of any triangle is calculated by the formula:

Thus, the area of this triangle is:

Example Question #7 : How To Find A Triangle On A Coordinate Plane

Triangle3

Given the above triangle has a base of  and hypotenuse of , find the height of the triangle. 

Possible Answers:

Correct answer:

Explanation:

Use the Pythagorean Theorem, 

 

where  is the hypotenuse,  is the base, and  is the height.

Rearranging to solve for the height, , yields:

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