Jawabanmu

Jawaban paling cerdas!
2014-05-18T22:43:15+07:00
1. 1- 2(sin2x)^2 - sin2x = 0--->2(sin2x)^2 + sin2x - 1 = 0\
(sin2x +1)(2sin2x - 1) = 0
sin2x + 1 = 0--->sin2x = -1 ---> 2x = 270, 630 --->x = 135, 315
2sin2x - 1 = 0 ---> sin2x = 1/2 --->2x = 30, 150, 390, 510
---> x = 15, 75, 195, 255

2. 3 cos(2x) − cos x + 2 = 0
3 (2 cos²x − 1) − cos x + 2 = 0
6 cos²x − 3 − cos x + 2 = 0
6 cos²x − cos x − 1 = 0
(3 cosx + 1) (2 cosx − 1) = 0

3 cosx + 1 = 0
cosx = −1/3
x = arccos(−1/3), 360 − arccos(−1/3)
x = 109.47°, 250.53°

2 cosx − 1 = 0
cosx = 1/2
x = 60°, 300°


3. tidak tau :D

semoga membantu ^_^
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