Cofunction identities  Trigonometric Identities
Cofunction identities
Related concepts:
 Sine graph: y = sin x
 Cosine graph: y = cos x
 Tangent graph: y = tan x
Lessons
Notes:
Cofunction Identities: Basically, we need the sum of the left and right brackets to be 90° or $\frac{\pi}{2}$
$\sin(\frac{\pi}{2}\theta)=\cos(\theta)$
$\sin(\theta)=\cos(\frac{\pi}{2}\theta)$
$\tan(\frac{\pi}{2}\theta)=\cot(\theta)$
$\tan(\theta)=\cot(\frac{\pi}{2}\theta)$
$\sec(\frac{\pi}{2}\theta)=\csc(\theta)$
$\sec(\theta)=\csc(\frac{\pi}{2}\theta)$

2.
Solve for $x$