Posted by **Sydney** on Sunday, May 17, 2009 at 3:08pm.

Hi, I'm really having problems with this question, can someone please help me. Thank-you!

Algebraically solve for 0<phaeta<2pi, 2cos^2 phaeta-7 cos phaeta +3=0

- Math -
**Reiny**, Sunday, May 17, 2009 at 3:31pm
allow me to use x instead of 'phaeta' for ease of typing, so

cos^2 x - 7cosx + 3 = 0

(2cosx - 1)(cosx - 3) = 0

cosx = 1/2 or cosx = 3, the latter not possible.

if cosx=1/2,then x = pi/3 or 5pi/3 (60º or 300º)

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