4(2cosx + 1) = 0
therefore:
2cosx = -1
cosx = -1/2
(2nd and 3rd quadrants bcoz its negative)
x = 120
and 180 + 60 = 240
x = 120, 240
2007-11-20 17:59:56 · 13 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
cos x = - 4 / 8 = - 1 / 2
x = 120° , x = 240° (as per your solution)
2007-11-20 20:27:29 · answer #1 · answered by Como 7 · 2⤊ 2⤋
It is correct but you could also do this:
8cos x+ 4 =0
8cos x = -4
cos x = -4/8 = -1/2
2007-11-20 18:08:54 · answer #2 · answered by smarties 6 · 0⤊ 1⤋
Perfect.
2007-11-20 18:05:33 · answer #3 · answered by Anonymous · 0⤊ 1⤋
I agree. Perfect. Only comment is you could save one step by just subtracting 4 from each side and dividing by 8. Results are same. You could have done it without factoring.
2007-11-20 23:26:43 · answer #4 · answered by duffy 4 · 0⤊ 2⤋
very good - 4 (8cosx) + 4 =0
2007-11-20 18:30:03 · answer #5 · answered by V B 5 · 0⤊ 2⤋
its perfect but can be done in a diff. way.
4(cos x+1)=cos (2n-1)pi/2.....
try it out
2007-11-20 19:07:34 · answer #6 · answered by Rogger.. 2 · 0⤊ 1⤋
Very nice
2007-11-20 20:40:56 · answer #7 · answered by Kishore k 2 · 0⤊ 2⤋
perfect buddy go ahead
2007-11-24 15:18:02 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Solution and reasoning are perfectly alright.
2007-11-21 00:23:10 · answer #9 · answered by Pramod Kumar 7 · 0⤊ 2⤋
Good work. This answer is correct.
2007-11-21 00:53:34 · answer #10 · answered by twinkle 2 · 0⤊ 2⤋