Question 1033133
I don't really understand the double-angle or the half-angle formula. Here are some problems I need to do:

1. If cos x = and x is a fourth-quadrant angle, evaluate sin 2x.
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No value is given for cos(x).
{{{sin(x) = sqrt(1 - cos^2(x))}}} --  that's Pythagoras, you have to know that.
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There are sites that show the derivation of half-angles and double angles, but that's not usually necessary.
sin(2x) = 2*sin(x)*cos(x)
You can remember that, or look it up.
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These are my answer choices:
*-sqrt(2)
*-1
*1
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2. If theta is a first-quadrant angle in standard position with 
P(u,v) = (3,4), evaluate tan(theta).
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tan = y/x = 4/3
Not one of the choices.
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Answer choices:
*1/4
*1/2
*2/3