Question

How to find the value of sin[2cos^-1(-3/5)] without using calculator??

Answer 1

Let \[\cos^{-1}\frac{-3}{5} = A \implies \cos A = \frac{-3}{5} \implies \cos^2 A = \frac{9}{25}\]

\[\cos^2 A + \sin^2 A = 1 \implies \sin A = \sqrt{1-9/25} = \frac{4}{5} \]

We cant to find \[\sin 2A \] which is equal to \[2\sin A \cos A \].


Gogogogogogog

Answer 2

Anwer is -24/25 and when i use with calculator it gives me that number...

Answer 3

Cool; I did it without a calculator, using the method above, because I'm not a three year old baby.

Answer 4

So what is your answer at then end of your method??
4/5??

Answer 5

ah so just plug 4/5 to the equation
i got it thanks

Answer 6

No.. The answer is 2 * sin A * cos A.

And I told you sin A = 4/5 and cos A = 3/5.

Answer 7

cos A = -3/5 ***

Answer 8

Thank you