Math, asked by venkatakash2004, 5 months ago

show that cosA=cos3A/2cos2A-1 hence find the value of cos15

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Answered by kattytayde

1

given: cosA = cos3A/2cos2A -1

so that cos15= cos3(15)/2cos2(15)-1

cos15= cos45/2cos30-1

cos 15= 1/√2/2*√3/2-1

cos15 =1/√6-√3

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