Double and Half Angle Identities Worksheet

Double and Half Angle Identities

Read each question carefully and answer to the best of your ability. Show all your work for full credit.

1. Which of the following is equivalent to sin(2x)?

2. If cos(θ) = 3/5 and θ is in Quadrant I, what is sin(2θ)?

3. The identity for cos(2x) can be expressed as cos²(x) - sin²(x), or  , or  .

4. The half-angle identity for sin(x/2) is ±√((1 - cos(x)) /  ).

5. Given tan(θ) = -4/3 and θ is in Quadrant II, find the exact value of sin(θ/2).

6. The identity tan(2x) = (2tan(x))/(1 - tan²(x)) is always true for all values of x.