Math21 Trigonometry Double, Half-Angle Identities

If sinθ = 1/3, and 0<θ<π/2, find the exact value of tan2θ

(4√2)/7

If sinθ = 1/3, and 0<θ<π/2, find the exact value of sin2θ

(4√2)/9

If secθ = -4/3, and 90°<θ<180°, find the exact value of sin2θ

-(3√7)/8

Use a half-angle identity to find the exact value of cos(7π/12)

-√(2-√3)/2

If secθ = -4/3, and 90°<θ<180°, find the exact value of cos2θ

1/8

Use a half-angle identity to find the exact value of tan(5π/12)

2 + √3

If secθ = -4/3, and 90°<θ<180°, find the exact value of tan2θ

3√7

If sinθ = 1/3, and 0<θ<π/2, find the exact value of cos2θ

7/9

If θ is an angle in Quadrant I, and cosθ = 1/4, find tan(θ/2)

√(15)/5

Use a half-angle identity to find the exact value of tan(π/8)

√(2) - 1

Use a half-angle identity to find the exact value of cos15°

√(2+√3)/2

Use a half-angle identity to find the exact value of sin(π/8)

√(2-√2)/2