6. Bobby was proving the law of cosines and reached a point where he had the equation 6² = c² sin² (B) + c² os² (B) + a² — 2ac cos(B). - COS Which of the following steps are needed to complete the proof? Select all that apply. Foil for b² =h² + a² - 2ax + x². Factor c² for b² = c² [sin²(B) + cos²(B)] + a² − 2ac cos(B). Use the Pythagorean theorem to result in b² = h² + (a − x)². - Use the trigonometric identity sin²+ cos² = 1 for b² = c² + a² - 2ac cos(B).

ne left 0:56:40 stion 21 dy If y= tan(2cos3x), then dx yet wered ed out of Select one: a. g question -6sec2(2cos3x).(sin3x) Ob. -6sec2(cos3x).(sin3x) C. -6sec2(sin(2cos3x)) d. -6sec2(2sin3x). (sin3x)

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2. Write the expression in terms of x and y only. You do not need to rationalize your answer, however, write your answer as one fraction. sin (cos-1 x – tan-1 4y)

17) Find the sin(15°), cos(15º) and tan(15°). Use these formulas. Leave answers in radical format. sin(u v) = sin(u)cos(v) ± cos(u)sin(v) cos(u + v) = cos(u)cos(v) -/+ sin(u)sin(v) tan(u) + tan (v) sin (6) tan(u + v) =- or tan(0) = 1-/+ tan(u)tan (v) cos (e

3. Describe the method used to integrate sinx. Choose the correct answer below. A. Rewrite sin ³x as (1 - cos²x) sinx, then use a half-angle formula to rewrite the cos ²x term. 3. B. Rewrite sin ³x as (1 - cos²x) sinx, then use the substitution u = cos x. C. Rewrite sin ³x as (sin ²x) sinx, then use a half-angle formula to rewrite the sin ²x term. 3 3 D. Rewrite sin ³x as tan ³x cos ³x, then use the substitution u = cos X. X,