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Olivia B.

asked • 12/11/13

Q2 POW #3 -Trig Identities

1) given the double angle identity for cosine: cos2θ=cos2θ-sin2θ
     Prove: cos3θ = cos3θ - 3cosθsin2θ
        and: cos4θ = cos4θ - 6cos2θsin2θ + sin2θ
2) Continue this process, finding an identity for cos5θ and cos6θ.
3) By examining the above identities (and a few more if needed), try to identify a pattern in order to generalize an identity for cosnθ.

(HINT: You will need to look at Pascal's Triangle.)

2 Answers By Expert Tutors

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Robert J. answered • 12/11/13

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4.6 (13)

Certified High School AP Calculus and Physics Teacher

Steve S. answered • 12/11/13

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5 (3)

Tutoring in Precalculus, Trig, and Differential Calculus

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