Question

3.) Simplify the expression.

Answer 1

Answer:

Option C) -cosu is correct

Therefore the simplified expression is $cos(u+\pi)=-cosu$

Step-by-step explanation:

Given expression is $cos(u+\pi)$

To find the value of the given expression :

By using the formula $cos(A+B)=cosAcosB-sinAsinB$

Substitute A=u and $B=\pi$ in the above formula we get

$cos(u+\pi)=cosucos\pi-sinusin\pi$

$=cosu(-1)-sinu(0)$  ( here $cos\pi=-1$ and $sin\pi=0$ )

$=-cosu-0$

$=-cosu$

$cos(u+\pi)=-cosu$

Therefore option C) -cosu is correct

Therefore the simplified expression is $cos(u+\pi)=-cosu$