Question

Please help me with this question

Answer 1

cos(x - 3 pi /2)= -7/25

Explanation:

Lets remember the following relationship.

cos(a-b)=cos(a)*cos(b)+sin(a)*sin(b)

if we evaluate 'a'= x and b=3 pi /2 we have:

cos(x-3 pi /2)=cos(x)*cos(3 pi /2)+sin(x)*sin(3 pi /2)

Since cos(3 pi /2)=0, sin(3 pi /2)=-1

We have

cos(x - 3 pi /2) =-sin(x)

Since sin(x) = 7/25 as stated in the problem, we have the final result:

cos(x - 3 pi /2)= -7/25