Question 520091
Prove the following equations is an identity. 
csc f/ cos f - cos f/sin f = tan f
**
start with left side
csc f/ cos f - cos f/sin f
LCD: sin cos
(csc sin-cos^2)/sin cos
(1-cos^2)/sin cos
sin^2/sin cos=sin/cos=tan
verified:
left side=right side