6. Trigonometric Identities and More Equations

Match each expression in Column I with its value in Column II.

8. tan (-π/8)

Match each expression in Column I with its value in Column II.

10. cos 67.5°

Use a half-angle identity to find each exact value.

sin 195°

Use a half-angle identity to find each exact value.

cos 195°

Use a half-angle identity to find each exact value.

sin 165°

Use the given information to find each of the following.

sin x/2 , given cos x = - 5/8, with π/2 < x < π

Use the given information to find each of the following.

cos θ/2 , given sin θ = - 4/5 , with 180° < θ < 270°

Use the given information to find each of the following.

cos x/2 , given cot x = -3, with π/2 < x < π

Use the given information to find each of the following.

cot θ/2, given tan θ = -(√5)/2 , with 90° < θ < 180°

Use the given information to find each of the following.

cos θ, given cos 2θ = 1/2 and θ terminates in quadrant II

If cos x = -0.750 and sin ≈ 0.6614, then tan x/2 ≈ .

Simplify each expression.

√[(1 + cos 165°)/(1 - cos 165°)]

Simplify each expression.

sin 158.2°/(1 + cos 158.2°)

Simplify each expression.

±√[(1 + cos 18x)/2]

Simplify each expression.

±√[(1 + cos 20α)/2]