# What is the value of sin -45^@?

##### 1 Answer
Jan 10, 2015

sin(-45°)=-sqrt(2)/2
This is the same as 45° but starting clockwise from the $x$ axis giving you a negative value of the $\sin$:

(Picture source: http://likbez.com/trig/Lesson01/)

or, if you like, is equal to a positive angle of 360°-45°=315°

(Be careful that for example $\cos \left(- 45\right) = \frac{\sqrt{2}}{2} > 0$)