Graphs of Sine and Cosine · Challenge problem

$4\cos\!\big(\tfrac{\pi}{3}(x-1)\big)+7$

$4\cos\!\big(\tfrac{3}{\pi}(x-1)\big)+6$

$4\cos\!\big(\tfrac{\pi}{3}(x-1)\big)+6$

$4\cos\!\big(\tfrac{\pi}{3}(x-1)\big)-6$