Trigonometry
posted by Greg on .
What value(s) of theta solve the following equation? cos^2(theta)cos(theta)6=0?
I try plugging in different numbers but I am not sure exactly what I am looking for in order to solve?

cos^2 Ø  cosØ  6 = 0
let cosØ = x , then we get
x^2  x  6 = 0
(x3)(x+2) = 0
x = 3 or x = 2
then cosØ = 3 or cosØ = 2
both of these are not possible, since the cosine is defined only between 1 and +1
there is no solution to your equation 
also, you coul dhave reasoned thus:
cos^2θ <= 1
1 <= cosθ <= 1
no way could you have cos^2θ  cosθ = 6