Math, asked by rohit6221, 1 year ago

question number 19 Rs Aggarwal exercise 11

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Answered by Erica03
1
Hey there ur answer is here..

Given Formula : cosA = √1 + cos2A / 2
Also, cos60 = 1/2
Required to find : cos30

Now,
Let A = 30 , 2A = 60°

cosA = √1 + cos2A / 2

cos30 = √( 1 + 1/2 ) / 2

cos30 = √(3/2)/2

cos30 = √(3/4) = √3 / 2

Therefore , cos30 = √3 / 2 

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