- #1
Neopets
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Homework Statement
SinA is = to -3/5 with A in Q3, find sinA?
Homework Equations
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. :( :(