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question mark

if tan^2a=2tab^2b +1 then cos2a +sin^2b is equal to?

varun , 6 Years ago
Grade 12th pass
anser 3 Answers
Arun
tan^2 A = 1 + 2tan^2 B 
=> sin^2 A / cos^2 A = 1 + 2 sin^2 B / cos^2 B 
=> sin^2 A / cos^2 A = (cos^2 B + 2sin^2 B) / cos^2 B 
=> sin^2 A cos^2 B = cos^2 A (cos^2 B + 2 sin^2 B) 
=> sin^2 A (1 - sin^2 B) = (1 - sin^2 A) (1 - sin^2 B + 2 sin^2 B) 
=> sin^2 A - sin^2 A sin^2 B = (1 - sin^2 A) (1 + sin^2 B) 
=> sin^2 A - sin^2 A sin^2 B = 1 - sin^2 A + sin^2 B - sin^2 A sin^2 B 
=> 2 sin^2 A = 1 + sin^2 B 
 
2 - 2 sin^2 A = 2 -(1 + sin^2 B)
2 cos^2 A = cos^2 B
Last Activity: 6 Years ago
Saurabh Koranglekar
Dear student

Please find the link below

https://www.askiitians.com/forums/Trigonometry/if-tan-2a-1-2tan-2b-then-prove-that-cos-2-b-2-c_194497.htm

Regards
Last Activity: 6 Years ago
Vikas TU
Dear student 
Good Luck 
Last Activity: 6 Years ago
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