Question

Verify cos3=4cos^3A - 3cosA ,when A=30°

Answer 1

HEY MATE!

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HERE IS YOUR ANSWER

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cosA3=4cos^3A-3cosA given:A=30°

cosA3=4*(√3/2)²-3(√3/2) cos30°=√3/2

cosA3=4*3√3/8-3√3/2

cosA3=3√3/2-3√3/2

cosA3=0

cos30°*3=0

cos90°=0

0=0 cos90°=0

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