GMAT Math : Calculating the area of a right triangle

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1 : Calculating The Area Of A Right Triangle

In the above figure, triangle SPQ, SPR and PRQ are right triangles. Given the lengths of SP and PQ are 2cm. What is the area of triangle SPR?

Possible Answers:

Correct answer:

Explanation:

Since  are right triangles, we know that  is an isosceles right triangle. So we know that the lengths of  and  are 2 cm, so we can get the length of  by using the Pythagorean Theorem:

 is the midpoint of , so the length of  is .

Now we can use the Pythagorean Theorem again to solve for : .

Finally, we have all the elements needed to solve for the area of :

Example Question #2 : Calculating The Area Of A Right Triangle

If a right triangle has a hypotenuse that is 10, and one side is 6, find the area of the triangle.

Possible Answers:

Correct answer:

Explanation:

Becaue this is a right triangle and since the hypotenuse is 10 and one side is 6, the other side will be 8.  This can be found using the Pythagorean Theorem, or multiplying a 3-4-5 triangle by 2 to get a 6-8-10 triangle.  Since the area of a right triangle is half of the product of the two sides, we have 

Example Question #3 : Calculating The Area Of A Right Triangle

The hypotenuse of a  triangle is equal to the sidelength of a square. Give the ratio of the area of the square to that of the triangle.

Possible Answers:

Correct answer:

Explanation:

Let  be the sidelength of the square. Then its area is .

If the hypotenuse of a  triangle is , its shorter leg is half that, or ; its longer leg is  times the shorter leg, or . The area of the triangle is half the product of the legs, or 

The ratio of the area of the square to that of the triangle is

 or 

 or 

Example Question #4 : Calculating The Area Of A Right Triangle

A triangle on the coordinate plane has vertices.

Which of the following expressions is equal to the area of the triangle?

Possible Answers:

Correct answer:

Explanation:

This is a right triangle with legs along the - and -axes, so the area of each can be calculated by taking one-half the product of the two legs. 

The vertical leg has length ; the horizontal leg has length .

Now calculate the area:

Example Question #5 : Calculating The Area Of A Right Triangle

Calculate the area of the following right triangle, leave in terms of

7

 

(Not drawn to scale.)

Possible Answers:

Correct answer:

Explanation:

The equation for the area of a right triangle is:

 

In this case, our values are: 

Plugging this into the equation leaves us with:

which can be rewritten as 

Example Question #6 : Calculating The Area Of A Right Triangle

A right triangle has a hypotenuse of 13 and a base of 12. Calculate the area of the triangle.

Possible Answers:

Correct answer:

Explanation:

In order to calculate the area of a right triangle, we need to know the height and the base. We are only given the length of the base, so we first need to use the Pythagorean theorem with the given hypotenuse to find the length of the height:

Now that we have the height and the base, we can plug these values into the formula for the area of a right triangle:

Example Question #7 : Calculating The Area Of A Right Triangle

Find the area of a triangle whose base is  and height is .

Possible Answers:

Correct answer:

Explanation:

To find the area, use the following formula:

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