Question

Cosa/(1+sina)+cosa/(1-sina)=2seca
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Answer 1

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Explanation:

Using the difference of two squares, the lowest common multiple becomes;

1-sin^2 a

Thus, we have that;

cos a (1-sin a) + cos a (1 + sin a) /1 - sin^2 a

1 - sin^2 a = cos^2 a

That means;

{cos a - cos a sin a + cos a + cos a sin a}/ cos^2 a

= 2cos a / cos^2 a

= 2/cos a

but 1/cos a = sec a

Thus;

2/ cos a = 2 sec a