Module 5 Quiz: Trigonometric Identities
Test Your Knowledge
10 questions on trig identities and formulas.
1
cos(A+B) = ?
cosAcosB − sinAsinB
2
sin2θ = ?
2sinθcosθ
3
Find cos15° exactly.
cos(45−30) = (√6+√2)/4
4
cos2θ has how many equivalent forms?
3: cos²−sin², 2cos²−1, 1−2sin²
5
sin²x = ? (power-reducing)
(1 − cos2x)/2
6
Verify: secθ − cosθ = sinθtanθ
LHS = 1/cos − cos = (1−cos²)/cos = sin²/cos = sin·(sin/cos) = sin·tan.
7
tan(A−B) formula?
(tanA − tanB)/(1 + tanAtanB)
8
Write sin3x cos2x as a sum.
(1/2)[sin5x + sinx]
9
cos(θ/2) = ? (half-angle)
±√[(1+cosθ)/2]
10
cosA+cosB as a product?
2cos((A+B)/2)cos((A−B)/2)