Question

Solve the equation 3sin^2 x + 4 cos x - 4 = 0. x < 90 degrees

Answer 1

Tip : write sin^2x = 1-cos^2x and then try to solve the quadratic

Answer 2

did you get that @4meisu ?

Answer 3

Kind of, not really though..

Answer 4

3(1-cos^2x)+4cosx-4=0
3-3cos^2x+4cosx-4=0
let (cosx)=X
then

3X^2+4X-1+0
then try to solve this and eleminat one of the tow solution ....

Answer 5

Would the answer be cos =1/3 , 1?

Answer 6

no that means that cosx=1/3
then search for x=cos^-1(1/3) search for ....you 'll get
I dont remember just use a calculater to find it