# Question #03cdf

##### 1 Answer

Aug 4, 2015

Take an equilateral triangle with sides , say a, and draw a perpendicular to the base from opposite vertex. The angles of each of the triangles are 30,60, 90 with sides a, a/2 and

(

#### Explanation:

Now cos 30 = {(

sin 30 = (a/2)/a = 1/2 etc.

sin 60 = cos 30 =

For trigonometric functions of 90, we consider a unit circle and proceed.

Note : too long a quest to give a comprehensive answer