solve: 2 cosx = -1?

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2007-11-05 09:04:06 · 3 answers · asked by Adam P 1 in Science & Mathematics ➔ Mathematics

cos x = - 1 / 2
x = 120° , x = 240°

2007-11-05 09:18:14 · answer #1 · answered by Como 7 · 1⤊ 0⤋

2 cosx = -1
cos x = - 1/2
x = 180 - 60 = 120 deg . . and . . x = 180+60 = 240 deg

2007-11-05 09:08:51 · answer #2 · answered by CPUcate 6 · 0⤊ 0⤋

you first divide the -1 by the 2 at the other side which is -0.5 the u find cos-1(-0.5) which is 60 degrees. Its pretty easy :D

2007-11-05 09:07:49 · answer #3 · answered by Anonymous · 0⤊ 0⤋