cosθ = 3 cosθ -1
for the above, what do I need to do to find θ = ?
2007-03-27 22:07:40 · 4 answers · asked by mischavee 2 in Science & Mathematics ➔ Mathematics
cosθ-3cosθ=-1
-2cosθ=-1
coθ=1/2
θ=arccos1/2
θ=+,-π/3;
2007-03-27 22:43:32 · answer #1 · answered by djin 2 · 0⤊ 0⤋
1 = 2.cos Ã
cos à = 1/2 and cosà is + ve
à is in 1st and 4th quadrants
à = 60°, 300° (à = Ï/3,5Ï/3)
P.S. I have used à because I don`t know how to find theta!?
2007-03-28 05:15:55 · answer #2 · answered by Como 7 · 0⤊ 0⤋
cosx=3cosx-1
-->cosx-3cosx=-1
-->-2cosx=-1
-->cosx=1/2
-->cosx=cos(60 degree)
-->x=60degree+k*360 degree(k is an integer)
or x=(-60 degree)+k*360 degree(since cosx=cos(-x))
If the question give you the interval of x,then you substitute the value of k respectively k=+-2,+-1,0 to get the suitable value of x.
2007-03-28 05:48:43 · answer #3 · answered by beuuu 2 · 0⤊ 0⤋
trial and error method
2007-03-28 05:43:09 · answer #4 · answered by Anonymous · 0⤊ 0⤋