Lesson: Special Right Triangles

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For the following question, can you please tell me why we are adding root 2 for the perimeter?


The hypotenuse of a right triangle is 10 cm. What is the perimeter, in centimeters, of the triangle?

(1) The area of the triangle is 25 square centimeters.
(2) The 2 legs of the triangle are of equal length.
gmat-admin's picture

Hi santhosh1989,

Here's my step-by-step solution to that question: https://gmatclub.com/forum/the-hypotenuse-of-a-right-triangle-is-10-cm-w...


In the below problem, how do one deduce the 30-60-90 triangle from the given info. What property am I missing. I could assume it will form a right angle, say 90 and then deduce 30 (180 - 90-60= 30).

Thanks in advance

gmat-admin's picture

Good question!

First, we're told that the ladder forms a 60-degree angle with the ground.

Second, the height of any triangle is the length of the line from the top of the triangle to the base, SUCH THAT this line is perpendicular to the base (see Jeff's diagram here: https://gmatclub.com/forum/a-ladder-of-a-fire-truck-is-elevated-to-an-an...)

Does that help?


Hi Brent,

Could you please help me understand the approach adopted to solve the following question:


gmat-admin's picture

You bet.

Here's my step-by-step solution: https://gmatclub.com/forum/figures-x-and-y-above-show-how-eight-identica...

Please let me know if you have any questions.


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