1. Fundamental Trig Identities
I. Fundamental Trig Identities.
A) Reciprocal identities.
B) Quotient identities.

2. Fundamental Trig Identities
I. Fundamental Trig Identities.
C) Pythagorean identities.

3. Fundamental Trig Identities
I. Fundamental Trig Identities.
D) Even / Odd identities.
E) Cofunction identities.

4. Fundamental Trig Identities
II. Using Identities to Evaluate Trig Functions.
A) Evaluate all 6 trig functions given one trig value.
1) The 6 trig functions
(sin, cos, tan,
csc, sec, cot)
2) Use x2 + y2 = r2
to find x, y & r.
3) Determine which
quadrant you are in and what signs x, y & r
will be in that quadrant.
4) Write the 6 trig identities with the correct signs.
(Rationalize the denominator, reduce fractions
and simplify double signs.)

5. Fundamental Trig Identities
III. Using Trig Identities to Simplify Trig Expressions.
A) Try converting everything to sine and cosine and simplifying (canceling out terms).
B) Try using one of the trig identities to rewrite the expression.
C) Try factoring out a GCF (Greatest Common Factor) or Factor using some other method.
D) Don’t give up. Try something.
E) There is often more than one way to simplify a trig expression.