HhEeLlPp! please?

1 ⤊

Let sin(x) = -(3/5) with (x) in Quadrant III and find

1. cos 2(x)

help! i don't know how to set this up and solve... if someone can show me using double-angle formulas... i will be able to find out how to do the other problems..... THANKS

2006-12-10 10:49:18 · 2 answers · asked by lx88xl 1 in Science & Mathematics ➔ Mathematics

2 answers

cos2x = 1 - 2sin^2 x = 1 - 2 * (-3/5)^2 = 7 / 25

2006-12-10 10:51:50 · answer #1 · answered by James Chan 4 · 1⤊ 0⤋

sin(x) = -(3/5)
x=sin^(-1)(-3/5)
x=-38.8698

cos 2x
=cos 2(-38.8698)
=0.28

2006-12-10 18:56:20 · answer #2 · answered by angel 2 · 0⤊ 0⤋