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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