This past week we went into 10-2. Chapter 10-2 is similar to 10-1 with alpha and beta. Since 10-1 was sine and cosine, 10-2 is tangent.

FORMULAS:
tan(alpha+beta)=tan alpha+tan beta/1-tan alpha tan beta
tan(alpha-beta)=tan alpha -tan beta/1+tan alpha tan beta

Cotangent is just a reciprocal of these formulas.

EXAMPLE:
simplify.
tan130 degrees-tan40 degrees/1+tan130 tan 40
*first you must find which formula matches and replace it.
tan(alpha-beta)
tan(130-40)
=tan 90 degrees
TRIG CHART!
your answer is undefined.

I had no problems with 10-1 and 10-2. It's basically plugging in and replacing formulas.