# What is #sin(x-90)#?

##### 1 Answer

Dec 17, 2015

#### Explanation:

Use the sine angle subtraction formula:

#sin(alpha-beta)=sin(alpha)cos(beta)-cos(alpha)sin(beta)#

Therefore,

#sin(x-90˚)=sin(x)cos(90˚)-cos(x)sin(90˚)#

#=sin(x)(0)-cos(x)(1)#

#=-cos(x)#