
Robert J. answered 01/03/14
Tutor
4.6
(13)
Certified High School AP Calculus and Physics Teacher
sin2x = 2sin x cos x
Solve 2sin x cos x = cos x for x,
cos x = 0, x = pi/2, 3pi/2
or
2sin x = 1
=> sin x = 1/2, x = pi/6, 5pi/6
Answer: x = pi/6, pi/2, 5pi/6, 3pi/2.