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2006-12-06 10:35:49 · 4 answers · asked by Eddy 2 in Science & Mathematics ➔ Mathematics
Factor out sin(x)
(sinx)(1+2cosx) = 0
sinx = 0 or 1 + 2cosx = 0
sinx = 0 when x = 0, pi (0 and 180 degrees)
1+ 2cosx = 0 when cosx = -1/2
cosx = -1/2 when x = 2pi/3, 4pi/3 (120 and 240 degrees)
2006-12-06 10:38:26 · answer #1 · answered by MsMath 7 · 0⤊ 0⤋
No
2sinx cosx = sin 2x
sin x + sin 2x is not zero if x = pi/2, for example.
Check the problem again.
2006-12-06 18:37:01 · answer #2 · answered by Anonymous · 1⤊ 0⤋
sin(x) + 2sin(x)cos(x) = 0
(sin(x))(1 + 2cos(x)) = 0
sin(x) = 0
x = 0° or 180°
1 + 2cos(x) = 0
2cos(x) = -1
cos(x) = (-1/2)
x = 120° or 240°
so
x = 0°, 120°, 180°, or 240°
2006-12-06 20:28:59 · answer #3 · answered by Sherman81 6 · 0⤊ 0⤋
sinx(1+2 cos x)=0
either sin x= 0
then x=180,
or
1+2 cos x= 0
cos x= -1/2
x=120,240
2006-12-06 19:01:12 · answer #4 · answered by niel_alinda 3 · 1⤊ 0⤋