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The value of (sec∅ − tan∅)² (1 + sin∅)² ÷ cos²∅ is
Question

The value of (sec∅ − tan∅)² (1 + sin∅)² ÷ cos²∅ is

A.

−2

B.

2

C.

0

D.

1

Correct option is D

Given:

 (sec∅ − tan∅)² (1 + sin∅)² ÷ cos²∅ 

 =(1cossincos)2×(1+sin)21sin2 =(1sincos)2×(1+sin)(1sin) =(1sin)2cos2×(1+sin)(1sin) =(1sin)2(1sin)(1+sin)×(1+sin)(1sin) =1= (\frac{1}{cos∅} − \frac{sin∅}{cos∅})² \times \frac{(1 + sin∅)² }{1 - sin^2∅}\\\ \\= (\frac{1 -sin∅}{cos∅})^2 \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= \frac{(1 -sin∅)^2}{cos^2∅} \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= \frac{(1 -sin∅)^2}{(1 -sin∅)(1 +sin∅)} \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= 1 

Identity Used: 

sin2θ+cos2θ=1sin^2\theta + cos^2 \theta = 1

Solution: 

 (sec∅ − tan∅)² (1 + sin∅)² ÷ cos²∅ 

=(1cossincos)2×(1+sin)21sin2 =(1sincos)2×(1+sin)(1sin) =(1sin)2cos2×(1+sin)(1sin) =(1sin)2(1sin)(1+sin)×(1+sin)(1sin) =1= (\frac{1}{cos∅} − \frac{sin∅}{cos∅})² \times \frac{(1 + sin∅)² }{1 - sin^2∅}\\\ \\= (\frac{1 -sin∅}{cos∅})^2 \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= \frac{(1 -sin∅)^2}{cos^2∅} \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= \frac{(1 -sin∅)^2}{(1 -sin∅)(1 +sin∅)} \times \frac{(1 + sin∅)}{(1 - sin∅)}\\\ \\= 1

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