Question 38300
I am not going to do your home work for you but i will give you a hint. 

A right triangle is triangle with an angle of 90 degrees (pi/2 radians). The sides a, b, and c of such a triangle satisfy the Pythagorean theorem
a^2+b^2==c^2,	(1)

where the largest side is conventionally denoted c and is called the hypotenuse. The other two sides of lengths a and b are called legs, or sometimes catheti.

The favorite A-level math exam question of the protagonist Christopher in the novel The Curious Incident of the Dog in the Night-Time asks for proof that a triangle with sides of the form n^2+1, n^2-1, and 2n where n>1 is a right triangle, and that the converse does not hold (Haddon 2003, pp. 214 and 223-226).
RightTriangle

The side lengths (a,b,c) of a right triangle form a so-called Pythagorean triple. A triangle that is not a right triangle is sometimes called an oblique triangle. Special cases of the right triangle include the isosceles right triangle (middle figure) and 30-60-90 triangle (right figure).

For any three similar shapes of area A_i on the sides of a right triangle,
A_1+A_2==A_3,	(2)

which is equivalent to the Pythagorean theorem.

For a right triangle with sides a, b, and hypotenuse c, the area is simply
A==1/2ab.