(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

SinA is = to -3/5 with A in Q3, find sinA?

2. Relevant equations

3. The attempt at a solution

When I did this I set it up like

First find cosA

So to do that I used plus/minus √(1-sin^2A)

The problem is that I really got confused when plugging in the values under the radical correctly, because i thought, -3/5 squared gives you positive 9/25 doesn't it and then the negative sign in the middle should make it 1-9/25, so you'd get 25/25-9/25 = 14/25

and then the answer also says that since it is in quadrant 3 it is negative, so -14/25 ? right?

Then plug that into the next step :

Sin 2A = 2SinACosA

=2(-3/5)(-√14/5)

something is wrong with how I'm doing it and I'd really like to know what. :( :(

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# Homework Help: Trig problem, let sinA= -3/5 wiht A in Quad. 3 find Sin2A

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