Question:
Use the symmetric and periodic properties of the sine, cosine and tangent functions to establish the following results.
$\displaystyle (a) \sin (90-\theta)^o = \cos \theta^o$
$\displaystyle (b) \sin (270 + \theta)^o = -\cos \theta^o$
$\displaystyle (c) \tan (\theta - 180)^o = \tan \theta^o$
Attempt:
I don't know how to start![]()