For a particular angle theta, the cosine function f(x)=a cos b(theta) has the following values with in one cycle of the function.
f(0)=4; f(pi/4)=0; f(pi/2)=-4; f(3pi/4)=0; f(pi)=4 what is the rule for the cosine function?
a. y=2 cos 4theta
b. y=4 cos 2theta
c. y=-4 cos 3theta
d. y= 1/4 cos 2theta

Question

For a particular angle theta, the cosine function f(x)=a cos b(theta) has the following values with in one cycle of the function. 
f(0)=4; f(pi/4)=0; f(pi/2)=-4; f(3pi/4)=0; f(pi)=4 what is the rule for the cosine function?
a. y=2 cos 4theta
b. y=4 cos 2theta
c. y=-4 cos 3theta
d. y= 1/4 cos 2theta

anonymous · Answer

@gibsonboy11

anonymous · Answer

@Nnesha

anonymous · Answer

@amistre64

amistre64 · Answer

what have you attempted?

anonymous · Answer

well it would help if i knew the first step.. @amistre64

amistre64 · Answer

plug in theta = 0, and compare results

amistre64 · Answer

you are given that f(0) = 4

4 = a cos(0)  what is a?

anonymous · Answer

ok how do i find a? is there like a formula?