Question

√(2)*cos^2(x)+sin(x)=0
find solution\find x

Answer 1

\[\sqrt{2}\times \cos x \times \cos x +\sin x =0\]
please help

Answer 2

use the identity cos^2 x = 1 - sin^2 x to get a quadratic equation in sin x

Answer 3

follow?

Answer 4

plug in (1 - sin^2 x) for cos^2 x

Answer 5

hey, didn't noticed you answered. thanks
but emm, the quad equation that came out is 2t^2 - t -2 = 0
no concrete solutions to that..

Answer 6

√2 - √2 sin^2x + sin x = 0
√2 sin^2 x - sin x - √2 = 0

Answer 7

yea, thats nice,
but how do I continue...? hehe

Answer 8

if you solve this using the quadratic formula you get

sin x = -1 / √2 or √2

as the sine of an angle must be between -1 and 1 the only possibility is - 1 / √2

Answer 9

so now you can find the possible values of x

Answer 10

yes!, got it right...
-45+360K \ 225+360K
thanks alot dude :)

Answer 11

yw