SOLUTION: Can someone please help me with this problem? Even after using the equation correctly, the results aren't right. If sin(x)=(7/8), x in quadrant I, then find (without finding x)

Question 607037: Can someone please help me with this problem? Even after using the equation correctly, the results aren't right.
If sin(x)=(7/8), x in quadrant I, then find (without finding x)
sin(2x)=
cos(2x)=
tan(2x)=
Thank you!
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
Use the double-angle formulas.

Here you need to find cos x. Since sin x = 7/8 and

then

(note that cos x > 0)

Plug everything in to obtain

Finding cos x is fairly simple. Use the identity

and replace sin x with 7/8.

Finding tan x is even simpler. Since tan x = (sin x)/(cos x), use the results you found in the previous two parts to find tan x.
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