Question

cos^2x-9cosx+20=0
find all solutions to the given equation.

Answer 1

Let y=cos(x), use quadratic formula (or factor it) to solve for y.

Answer 2

I got that so y= 5 or 4
but what next?

Answer 3

dont forget, the value maximum of cosx=1 and minumum -1
so, -1<= cosx <= 1. if out of that inteval "no solution"

Answer 4

the answer choices are
pi/3 +k(pi)
pi/2 +k(pi)
pi/4 +k(pi/2)
no solutions

Answer 5

ok so no solutions
got it
Thanks

Answer 6

wellcome :)