trig 30

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If cos^2 theta -6 sin 2 theta =0, one value of theta is a)0 degrees b) 90 degrees c)180 degrees or D)255 degrees.
Please show me how to do it and not just give answer cause I have two more questions that are similar. Thanks so much.

• trig 30 -

cos^2 Ø - 6sin 2Ø = 0
cos^2Ø - 12sinØcosØ = 0
cosØ(cosØ - 12sinØ) = 0
cos Ø = 0 or 12sinØ = cosØ
Ø = 90 degrees or ......

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