Question

2cos^2x+5sinx=4,find the value of x?

Answer 1

$2( {1 - \sin(x) }^{2} ) + 5 \sin(x ) = 4$
as cos²x=1-sin²x
2-2sin²x+5sinx=4
or,
2sin²x-5sinx+2=0
let sinx=t
then the equation becomes
2t²-5t+2
solving this quadratic equation we get
t=2,1/2
or
sinx=2,1/2
2 is neglected as maximum value of sinx is 1.
so sinx=1/2
or.x=π/6 or 5π/6
=30° or 150°

Answer 2

Answer:30degree

Step-by-step explanation: