1. Trigonometric Identities

2. Trigonometric Identities
Reciprocal Identities

3. Trigonometric Identities
Quotient Identities

4. Trigonometric Identities
Pythagorean Identities
Note: sin2 is (sin )2 not sin (2)

5. Example 5
Use trigonometric identities to transform one side of the equation into the other.
cossec=1
(sec+tan)(sec-tan)=1

6. Homework Practice

7. Surveying
A surveyor is standing 50 ft from the base of a large tree. The surveyor measures the angle of elevation to the top of the tree as 71.5°. How tall is the tree?

8. River Walk
You are 200 yards from a river. Rather than walking directly to the river, you walk 400 yards along a straight path to the river’s edge. Find the acute angle ө between this path and the river’s edge.

9. Skateboarding
Find the length c of the skateboard ramp.