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If cos A1−sin A+cos A1+sin A=4\frac{\text{cos}\space{\text{A}}}{1-\text{sin}\space\text{A}}+\frac{\text{cos}\space{\text{A}}}{1+\t
Question

If cos A1sin A+cos A1+sin A=4\frac{\text{cos}\space{\text{A}}}{1-\text{sin}\space\text{A}}+\frac{\text{cos}\space{\text{A}}}{1+\text{sin}\space\text{A}}=4​, then what will be the value of A?

A.

90°

B.

60°

C.

30°

D.

45°

Correct option is B

Given:

cosA1sinA+cosA1+sinA=4\frac{\cos A}{1 - \sin A} + \frac{\cos A}{1 + \sin A} = 4​​

Formula Used:
sin2A+cos2A=1.\sin^2 A + \cos^2 A = 1.​​

Solution:

cosA1sinA+cosA1+sinA=4\frac{\cos A}{1 - \sin A} + \frac{\cos A}{1 + \sin A} = 4​​

cosA(11sinA+11+sinA)=4\cos A \left( \frac{1}{1 - \sin A} + \frac{1}{1 + \sin A} \right) = 4​​

cosA((1+sinA)+(1sinA)1sin2A)=4\cos A \left( \frac{(1 + \sin A) + (1 - \sin A)}{1 - \sin^2 A} \right) = 4​​

cosA(2cos2A)=4\cos A \left( \frac{2}{\cos^2 A} \right) = 4​​

2cosA=4\frac{2}{\cos A} = 4

cos A =12= \frac{1}{2}

A = 60 60^\circ​​

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