Trigonometric Functions - Negative Values

Question

How do I solve for trigonometric functions where, instead of cos(49) or sin(68), just for example, the number is negative instead? Ex. cos(-49), sin(-68)

Answer 1

You can also use the fact that cosine is an even function and sine is an odd function.

So, cos(-49°) = cos(49°) and sin(-68°) = -sin(68°).

Answer 2

sin(x) and cos(x)

sin(–x) = –sin(x)

cos(–x) = cos(x)

Answer 3

Your calculator will accommodate for negative angles. They just mean that the angle on the unit circle is measured clockwise instead of counter clockwise. Be sure your calculator is set in degree mode if that is appropriate.

So Cos (-49°) = 0.300 and sin (-68)= .8979