# How do I solve this question?

##### 1 Answer

May 2, 2018

Let's assume a right-angled triangle ABC with base AB =

By Pythagoras theorem, we have:

BC is the perpendicular.

By definition, sin(t) is the ratio of the perpendicular to the hypotenuse of a right-angled triangle.

Since the sine of any angle is a constant, irrespective of side lengths, we may assume

(Note, we could have used the identity

The function cos(t) is symmetric about the y-axis. This means cos(-t) = cos(t)