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Trig help - FAST AND HARD!!!
I have to find where these two functions intersect.
g(x) = sin(2x) & f(x) = sin(x) so sin(2x) = sin(x) How do I solve for x? need exact value, not decimal. THANK YOU:icare: |
0, and 180 (degrees) both work, just by intuition, and i think i know how to actually work it out, but my brain isn't really working right now, so hold up...
edit: woops, i said 90 instead of 180. mistake corrected. |
Well, you should know the trigonometric identity, sin(2x) = 2 * sin(x) * cos(x).
This should be enough for you to solve the problem, yourself... |
Quote:
Thanks. And yeah, I SHOULD know the identity, but havn't had trig in years. (I'm actually in calc, rotating regions around a line and taking the integral to find the volume of da' soild) fun fun |
sin(2x) = 2sin(x)cos(x)
cos(2x) = 2cos^2(x) - 1 cos(2x) = 1 - 2sin^2(x) cos(2x) = cos^2(x) - sin^2(x) tan(2x) = 2tan(x) / 1 - tan^2(x) sin(x+y) = sin(x)cos(y) + cos(x)sin(y) sin(x-y) = sin(x)cos(y) - cox(x)sin(y) cos(x+y) = cos(x)cos(y) - sin(x)sin(y) cos(x-y) = cos(x)cos(y) + sin(x)sin(y) tan(x+y) = tan(x) + tan(y) / (1 - tan(x)tan(y)) tan(x-y) = tan(x) - tan(y) / (1 + tan(x)tan(y)) sin^2(x) = 0.5 - 0.5cos(2x) cos^2(x) = 0.5cos(2x) - 0.5 i think they're all correct, havent had to think about any of it for 4months.. hope they are, that'd mean i'd have less to worry about this year |
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