Please help! solve for x on [0,2pi), 2cos(2x)-1=0?

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2007-12-03 16:51:42 · 3 answers · asked by Mane Z 1 in Science & Mathematics ➔ Mathematics

cos 2x = 1/2
2x = π / 3 , 5 π / 3, 7π / 3 , 11π / 3
x = π / 6 , 5 π / 6, 7π / 6 , 11π / 6

2007-12-03 21:38:43 · answer #1 · answered by Como 7 · 0⤊ 0⤋

cos(2x) = 1/ 2

cos(2x) = 0.5

Graph it:

x= 30, 150, 210, 330 degrees

2007-12-03 16:57:44 · answer #2 · answered by GetDownWithThe$ickness 4 · 0⤊ 0⤋

2cos(2x)-1=0 x belongs[0,2pi)
cos2x=1/2
2x=pi/3, 2pi-pi/3=5pi/3, 2pi+pi/3=7pi/3, 4pi-pi/3=11pi/3
x=pi/6, 5pi/6, 7pi/6, 11pi/6

2007-12-03 17:06:28 · answer #3 · answered by Anonymous · 0⤊ 0⤋