Trig
posted by Anonymous on .
what are the intercepts of the graph of f(x)=4cos^2 3 on the interval [0, 2pi]?

I am sure you meant:
f(x)=4cos^2 x 3
for the xintercepts:
4cos^2 x 3 = 0
cos^2 x = 3/4
cos x = ±√3/2 > so x is in all 4 quadrants.
I know that cos π/6 = √3/2
so x = π/6, π  π/6, π + π/6, and 2ππ/6
or
x = π/6, 5π/6, 7π/6, and 11π/6
for the yintercept, let x = 0
f(0) = 4cos^2 0  3
= 4(1)  3 = 1