GMAT Math : Triangles

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1 : Calculating The Perimeter Of An Equilateral Triangle

Given the following regarding Triangle .

I) 

II) Side  is equal to  light-years

What is the length of side ?

Possible Answers:

 light years

 light years

 light years

 light years

 light years

Correct answer:

 light years

Explanation:

The trick to this one is to carefully put together what you are given.

We know that two of our angles are equal to 60 degrees. This means that the last angle is also 60 degrees. This make HFT an equilateral triangle.

Equilateral triangles always have equal sides and equal angles, so our last side has to be 7 light years as well. 

Example Question #21 : Equilateral Triangles

Calculate the perimeter of an equilateral triangle whose side length is .

Possible Answers:

Correct answer:

Explanation:

The perimeter of an equilateral triangle is:

Thus.

Example Question #22 : Equilateral Triangles

Find the perimeter of an equilateral triangle whose side length is .

Possible Answers:

Correct answer:

Explanation:

To find the perimeter, you must multiply the side length by . Thus,

Example Question #561 : Problem Solving Questions

Calculate the perimeter of an equilateral triangle whose side length is .

Possible Answers:

Correct answer:

Explanation:

To solve, simply multiply the side length by . Thus,

Example Question #1 : Acute / Obtuse Triangles

A triangle has 2 sides length 5 and 12.  Which of the following could be the perimeter of the triangle?

I. 20

II. 25

III. 30

Possible Answers:

All 3 are possible.

I and II only

I only

II and III only.

III only

Correct answer:

II and III only.

Explanation:

For a triangle, the sum of the two shortest sides must be greater than that of the longest.  We are given two sides as 5 and 12.  Our third side must be greater than 7, since if it were smaller than that we would have  where is the unknown side.  It must also be smaller than 17 since were it larger, we would have .

 

Thus our perimeter will be between and . Only II and III are in this range.

Example Question #2 : Acute / Obtuse Triangles

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Triangle  has sides . What is the perimeter of triangle ?

Possible Answers:

Correct answer:

Explanation:

To calculate the perimeter, we simply need to add the three sides of the triangle.

Therefore, the perimeter is , which is the final answer.

Example Question #3 : Acute / Obtuse Triangles

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Triangle  has height . If  is the midpoint of  and , what is the perimeter of triangle ?

Possible Answers:

Correct answer:

Explanation:

Since BD is the height of triangle ABC, we can apply the Pythagorean Theorem to, let's say, triangle DBC and .

Since the basis of the height is at the midpoint of AC, it follows that triangle ABC, is an isoceles triangle.

We can find the perimeter by multiplying BC by 2 and add the basis of the triangle AC, which has length of .

The final answer is therefore .

Example Question #4 : Acute / Obtuse Triangles

An acute triangle has side lengths of , and . What is the perimeter of the triangle?

Possible Answers:

Correct answer:

Explanation:

For any given triangle, the perimeter  is the sum of the lengths of its sides. Given side lengths of , and 

Example Question #5 : Acute / Obtuse Triangles

An acute triangle has side lengths of , and . What is the perimeter of the triangle?

Possible Answers:

Correct answer:

Explanation:

For any given triangle, the perimeter  is the sum of the lengths of its sides. Given side lengths of , and 

Example Question #6 : Acute / Obtuse Triangles

An acute triangle has side lengths of , and . What is the perimeter of the triangle?

Possible Answers:

Correct answer:

Explanation:

For any given triangle, the perimeter  is the sum of the lengths of its sides. Given side lengths of , and 

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