These are problems involving sinusoidal graphs:

$\displaystyle f(x)=-1+4cos\frac{\pi}{3}(x-0.5)$

(a) f(5)

(b) f(x)=1

$\displaystyle f(t)=50+20cos\frac{2\pi}{6}(x-0.5)$

(a) f(t)=50

(b) f(40) -- I'm supposed to identify where the sinusoidal graph has a value of 40 at 4 different points.