Question

sin 2A =?, when sinA=12/13

Answer 1

The correct answer to this question is $\frac{120}{169}$.

Given,

sinA=$\frac{12}{13}$

To Find,

sin2A.

Solution,

As we know that

sin2A=2SinAcosA

So,

sinA=$\frac{P}{H}$

So, here sinA=$\frac{12}{13}$

cosA=$\frac{B}{H}$

By using the Pythagoras theorem

B²=H²-P²

B²=13²-12²

B²=169-144

B²=25

B=5.

Now, we have values of P, H, and B.

cosA=$\frac{5}{13}$.

Then,

sin2A=2×$\frac{12}{13}$×$\frac{5}{13}$.

=$\frac{2*12*5}{13*13}$.

=$\frac{120}{169}$.

The correct answer to this question is$\frac{120}{169}$.

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