Posted by LiNnda on Monday, May 3, 2010 at 11:19am.
8sin^2x+sinxcosx+cos^2x=4

equations trig  Reiny, Monday, May 3, 2010 at 11:50am
very tricky
8sin^2x+sinxcosx+cos^2x=4
8sin^2x+sinxcosx+cos^2x=4(sin^2x + cos^2x)
8sin^2x+sinxcosx+cos^2x=4sin^2x + 4cos^2x
4sin^2x + sinxcosx  3cos^2x = 0
(sinx + cosx)(4sinx  3cosx) = 0
sinx = cosx or sinx = (3/4)cosx
sinx/cosx = 1 or sinx/cosx = 3/4
tanx = 1 or tanx = 3/4
x = 135°, 315° or x = 36.9° or 216.9°
if you want radians, change your calculator to rad

equations trig  LiNnda, Thursday, May 6, 2010 at 7:53am
thank u very much!
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