Question

F(x) = cos(x - 90°)
Which is the value of f(0°)?
A 1
B 0
C-1
1
2

Answer 1

The answer is B.
f(x)= cos(x-90) = -cos(90-x)
(If you know how to, draw the CAST chart)
-cos(90-x)= -sin(x)
Sub. x=0, -sin(0)= 0