Posted by **Carson** on Monday, March 25, 2013 at 8:04pm.

The values of x that are solutions to the equation cos^(2)x=sin2x in the interval [0, pi] are

a. arctan(1/2) only

b. arctan(1/2) and pi

c. arctan(1/2) and 0

d. arctan(1/2) and (pi/2)

e. arctan(1/2), o, and (pi/2)

- precal -
**Reiny**, Monday, March 25, 2013 at 9:07pm
cos^2 x - sin 2x = 0 , 0 ≤ x ≤ π

cos^2 x - 2sinxcosx= 0

cosx(cosx - 2sinx) = 0

cosx = 0

x = π/2

or

cosx = 2sinx

cosx/sinx = 2

sinx/cosx = 1/2

tanx = 1/2 , tan is positive only in I for our domain

x = arctan(1/2)

so it looks like D

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