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4cos12cos48cos72=cos36 |
| Answer» LHS =\xa04cos12cos48cos72 = 2 ( 2 cos\xa012cos48) cos 72 = 2 ( cos 60 + cos\xa036 ) cos 72 = 2cos 72 ( cos 60 + cos 36) = 2cos72cos60\xa0+ 2 cos72cos36 = 2 cos\xa072 * 1/2 + ( 2cos72 cos 36) = cos 72 + cos 108 + cos 36 = cos 72 + cos ( 180 - 72) + cos 36 = cos 72 - cos 72 + cos 36 = cos 36 = RHS\xa0Read more on Brainly.in - https://brainly.in/question/2057801#readmore | |