Math, asked by Sid234, 1 year ago

1 + cos56° + cos58° - cos66° =?
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Answered by aqibkincsem
30

1+ cos 56 = 2 cos^2 28 as cos 2t = 2 cos^2 t - 1 cos 58 = 2 cos^ 29 - 1 cos 66 = 2cos ^2 33 - 1 so 1+ cos 56 + cos 58 - cos 66 = 2 cos^2 28 + 2 cos^2 29 - 2 cos^2 33 = 2 ( cos^2 28 + cos ^2 29 - cos ^2 33)

now 28+29+33 = 90 in case we demonstrate cos ^2 A + cos^2 B - cos^2 c = 2 cos A cos B sin C when A+B+C = pi.2

Answered by pragneshparikh82
35

Answer:

Step-by-step explanation:

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