Am I allowed to open these brackets of t the angle?

Sin(X)Cos(90-V)
can it equal to sin(x)
(Cos(90)-cos(v))?????????????

1 Answer
Nov 28, 2017

Please see below.

Explanation:

.

I think you want to know if:

#cos(90-v)=cos90-cosv#

The answer is no. There is a formula for this:

#cos(a-b)=cosacosb+sinasinb#

Therefore:

#cos(90-v)=cos90cosv+sin90sinv#

#cos(90-v)=(0)(cosv)+(1)(sinv)=0+sinv#

#cos(90-v)=sinv#