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

Answer 1

Hello,

Answer B

y=4 cos(2θ)
Indeed,
 cos 0=1 ==>to make 4, a=4

cos (Π/4)=√2 /2 Or cos (π/2)=0==> b=2