If tan²A = 1+ 2tan²B Show: COS2B = 1+2 cos2A

asked Jul 26, 2021 5.2k views

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If tan²A = 1+ 2tan²B
Show: COS2B = 1+2 cos2A

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3 votes

Answer:

Explanation:

hello :

here is this idea :

tanA= sinA/cosA tanB= sinB/cosB

cos²A+sin²A =1 cos²B+sin²B =1

cos²A-sin²A=cos2A cos²B-sin²B=cos2B

Hiren Gamit answered Jul 31, 2021

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