Question

2.
If tan A = 2, find the value of cos 2A.​

Answer 1

Answer:

-3/5

Step-by-step explanation:

hello friend

cos2A = 1- tan²A/1+tan²A

= 1-(2)²/1+(2)²

= 1-4/1+4

= -3/5

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Answer 2

Answer:

Required value of Cos2A is $( - \frac{3}{5} )$

Step-by-step explanation:

Here given, $\tan(A) = 2$

We want to find value of $\cos(2A)$

We know by trigonometry formula,

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

We are putting tanA = 2,

$\cos(2A) = \frac{1 - {2}^{2} }{1 + {2}^{2} } \\ = \frac{1 - 4}{1 + 4} \\ = \frac{ - 3}{5} \\ = - \frac{3}{5}$

Therefore, required value of cos2A is $( - \frac{3}{5} )$

Some important Trigonometry formulas,

$sin(x) = \cos(\frac{\pi}{2} - x) \\ \tan(x) = \cot(\frac{\pi}{2} - x) \\ \sec(x) = \csc(\frac{\pi}{2} - x) \\ \cos(x) = \sin(\frac{\pi}{2} - x) \\ \cot(x) = \tan(\frac{\pi}{2} - x) \\ \csc(x) = \sec(\frac{\pi}{2} - x)$

Know more about trigonometry,

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