Question

find the value of theta
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Answer 1

Answer:

2 Sin² Ф + √3 cos Ф + 1 = 0

2 (1- cos²Ф ) + √3 cos Ф + 1 =0

multiply by -1 and rearrange

2 cos² Ф -√3 cos Ф - 3 = 0

Δ = 3 + 24 = 27

cos Ф = ( √3 +-  3 √3 ) /  4            =  √3  or  -√3 / 2

cos Ф cannot be √3 as it is > 1.

So  cos Ф = - √3/2  =>    Ф = in second and third quadrants. =  5π/6  or  7π/6

or 150 deg or 210 deg

Ф = 2nπ +-  5π/6    or  2nπ +- 7π/6

Answer 2

Answer:

here is your answer (◍•ᴗ•◍)✧*。

2sin²theta+√3cos theta+1=0

2(1-cos²theta)+√3cos theta+1=0

2-2cos²theta+√3cos theta+1=0

2cos²theta-√3cos theta-3=0

2cos²theta-2√3cos theta+√3cos theta-3=0

(cos theta-√3)(2cos theta+√3)=0

either, cos theta=√3(not applicable)

or, cos theta=-√3/2

cos theta= -cos 30°

cos theta= cos(180°+30°)=cos210°

or, cos theta=cos(180°-30°)=cos150°

so, theta=150°,210°✔️✔️

please mark it as brainlist if it helps ✨✨

Assamese girl✌️