Question

If cos 2a = tan^2 b,show cos 2b = tan^2 a

Answer 1

Proof :

Now, cos2a = tan²b

or, $\frac{cos2a}{1}=\frac{tan^{2}b}{1}$

or, $\frac{1-cos2a}{1+cos2a}=\frac{1-tan^{2}b}{1+tan^{2}b}$

or, tan²a = cos2b

or, cos2b = tan²a

Thus, proved.

Rules :

1. $\frac{1-cos2a}{1+cos2a}=tan^{2}a$

2. $\frac{1-tan^{2}b}{1+tan^{2}b}=cos2b$

Answer 2

Answer:

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