Question

solve the equation.

cos x(cos x - 1) = 0

Answer 1

Set each factor, independently, equal to 0 and solve for x
cosx = 0
cosx = 1
Now its just knowing which values of cosine equal 0 and 1.

Answer 2

Umm I still don't get it lol

Answer 3

=> cos x(cos x - 1) = 0

# solve for cos(x) , what do you get?

Answer 4

1 or 0??

Answer 5

well, yes, as @Psymon said, now look at your Unit Circle, where's cosine 0 and 1?
those are very well known angles

Answer 6

x=0, 90, 180, 270,360,450, 540,630

Answer 7

0 and 180?

Answer 8

x=k*90 where k is a integer

Answer 9

ummm so do I just pick one of the x values to substitute for k?

Answer 10

well, at 180 cosine is -1, not 1

Answer 11

\(\bf cos(x) = 1 \implies cos^{-1}(cos(x)) = cos^{-1}(1)\implies
x = 0^o\)

Answer 12

but wait! there's more!
-- taken from late night tv shows selling stuff--

Answer 13

lol oh?

Answer 14

0 degrees is only 1 revolution, that is 2pi
if you go around in circles, 4pi, 6pi, 8pi, 64pi ....
so the answer is like \(\bf x = n + 2\pi\) where "n" is an integer \(\ge 0\)

Answer 15

well, I guess it should be \(\bf x = 2\pi n\) rather

Answer 16

then you'd have to accomodate the other angle in the notation

Answer 17

sorry for mistake,

Answer 18

http://www.wolframalpha.com/input/?i=cos%28x%29*%28cos%28x%29-1%29%3D0 you can find easy solutions here to all of ur equation