Question

cos(pi/2-x)=sin(x)

True or False

Answer 1

false, doesn't work out

Answer 2

false

Answer 3

\(\cos(A-B) = \cos(A)\cos(B)+\sin(A)\sin(B)\)

So in fact
\(\cos(\dfrac{\pi}{2}-x)=\cos(\dfrac{\pi}{2})\cos(x)+\sin(\dfrac{\pi}{2})\sin(x)=0*\cos(x)+1*\sin(x)=\sin(x)\)

Answer 4

@plohrb @Dwayne_Johnson

This is the problem with just giving answers...

Answer 5

this is also cofunction identity
compare cos(pi-x) 's ratio and sin(x)'s ratio