Question

solve 2sin²x + 3cos x = 0

please answer correctly i will mark as brainliest.​

Answer 1

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Changing sin

2

x into 1−cos

2

x; we get

2(1−cos

2

x)+

3

cosx+1=0

or 2cos

2

x−

3

cosx−3=0

∴cosx=

4

3

±

3+24

=

4

3

+3

3

=

3

or

2

−

3

Since

3

is greater than 1 it is not admissible as cosx can not be greater than 1.

∴cosx=−

3

/2=−cos(π/6)

=cos(π−π/6)=cos(5π/6)

∴x=2nπ±(5π/6).