Posted by **Cynthia** on Friday, August 3, 2012 at 3:17pm.

Solve cos 2x – 3sin x cos 2x = 0 for the principal value(s) to

two decimal places.

Please explain.

- Trigonometry -
**Steve**, Friday, August 3, 2012 at 3:42pm
cos2x (1 - 3sinx) = 0

cos2x = 0 or sinx = 1/3

cos 2x = 0:

2x = k*pi/2 where k is an integer

x = pi/4, 3pi/4, 5pi/4, 7pi/4

sinx = 1/3:

x = 0.34 or pi-0.34

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