Question

if tanA=1/2, tanB=1/3, then cos2A=​

Answer 1

Hope....it goes right....

Answer 2

The value of cos 2A is 3/5.

Step-by-step explanation:

Given information: $\tan A=\dfrac{1}{2},\tan B=\dfrac{1}{3}$

We need to find the value of cos2A.

We know that

$\cos 2A=\dfrac{1-\tan^2 A}{1+\tan^2 A}$

Substitute $\tan A=\dfrac{1}{2}$ in the above equation.

$\cos 2A=\dfrac{1-(\frac{1}{2})^2}{1+(\frac{1}{2})^2}$

$\cos 2A=\dfrac{1-\frac{1}{4}}{1+\frac{1}{4}}$

$\cos 2A=\dfrac{\frac{4-1}{4}}{\frac{4+1}{4}}$

$\cos 2A=\dfrac{\frac{3}{4}}{\frac{5}{4}}$

$\cos 2A=\dfrac{3}{5}$

Therefore, the value of cos 2A is 3/5.

#Learn more

1-tan^2x/1+tan^2x=2 cos^2x-1

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