Posted by LiNnda on .
8sin^2x+sinxcosx+cos^2x=4

equations trig 
Reiny,
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,
thank u very much!