Write another possible formula for
y = −2 cos(3x + π) + 1 using the sine
function and a positive coeﬃcient on the sine.

Question

Write another possible formula for 
y = −2 cos(3x + π) + 1 using the sine 
function and a positive coeﬃcient on the sine.

myininaya · Answer

remember 
$$\cos(x)=\sin(\frac{\pi}{2}-x)$$
$$y=-2\sin(\frac{\pi}{2}-(3x+\pi))+1$$

myininaya · Answer

you can simplify that inside

anonymous · Answer

wait, so you have t plug it in? so how would you handle the pi in the original equation? ugh I'm really bad at all these identities.

myininaya · Answer

you have
$$y=-2\sin(\frac{\pi}{2}-3x-\pi)+1=-2\sin(\frac{\pi}{2}-\frac{2\pi}{2}-3x)+1$$
$$y=-2\sin(\frac{-\pi}{2}-3x)+1$$
and it also say to write with positive coeifficient 
so also recall that sin(-x)=-sinx
so we have 
$$y=-2\sin(-[\frac{\pi}{2}+3x])+1=-2*-\sin(\frac{\pi}{2}+3x)+1=2\sin(\frac{\pi}{2}+3x)+1$$