Chapter 2 : Solving Right Triangles
Topics covered in this snack-sized chapter:
A triangle in which one angle measures exactly 90° is called a Right Triangle.
The side opposite the right angle is called the Hypotenuse and the remaining two sides are called the Legs of the triangle.
In the above figure sides a, b are legs of triangle and side c is hypotenuse.
Pythagoras Theorem states that:
In a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.
Proof:
Let a 
, right angled at 
.
We need to prove that
Let us draw 
Now, 
So, 
………
Also, 
So, 
………
Adding 
and
:
The six ratios of a right triangle are called Trigonometric Functions of acute angles and are defined as follows:
Example: Find the value of each of the six trigonometric functions of the triangle shown below:
Solution:
By Pythagorean Theorem:
So,
