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August 20, 2014

Homework Help: RESPONSE to PreCalc Question

Posted by Kate RESPONSE on Monday, March 1, 2010 at 12:10am.

h t t p : / / w w w . j i s k h a . c o m / d i s p l a y . c g i ? i d = 1 2 6 7 4 1 7 1 8 8

I don't follow your work Reiny

3sinx + cosx = 1
3cosx = 1-cosx
square both sides
3cos^2 x = 1 - 2cosx + cos^2 x
3(1-sin^2 x) = 1 - 2cosx + cos^2 x
this reduces easily to
2cos^2 x - cosx - 1 = 0
(2cosx + 1)(cosx - 1) = 0
cosx = -1/2 or cosx = 1
x or theta = 120 , 240 or 0 , 360
x = 0, 2pi/3, 4pi/3, 2pi

Line 2 you subtracted cos x form both sides

3sinx + cosx = 1
3cosx = 1-cosx
how did the sin x next to the SQRT(3) change to cos x magically...

I don't think I'm seeing something here that I should be...

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