Question

How do I solve sin^2 x = -2cos x?

Answer 1

change sin^x in to cos x, you will have quadratic equation in cos x

Answer 2

Remember, sin^2 x+cos^2 x=1

Answer 3

solve the above equation that I gave you for sin^2 x, substitute, and do as experimentX has instructed.

Answer 4

sinx^2+cosx^2=1
\[\sin x =\sqrt{1-\cos^2}\]
then u can easily solve it

Answer 5

So \[\sin ^{2}x=1-\cos ^{2}x\]? And then I replace sin^2x with that?

Answer 6

Yes

Answer 7

So I wind up with cos^2 x – 2cos x – 1 = 0 and factor it as (cos x – 1)(cos x + 1) then solve?

Answer 8

No, it doesn't factor that way.

Answer 9

Add two to both sides to get
cos^2 x-2cos x+1=2
then take the square root of both sides
(cos x-1)=plus minus (sqrt 2)

Answer 10

Ah! So confusing.....thank you for you help...I appreciate it

Answer 11

Also can be left as

cosx(cosx-2) =1