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Question
(secA + tanA) (1 − sinA) = ______.
Options
sec A
sin A
cosec A
cos A
Solution
(secA + tanA) (1 − sinA) = cos A.
Explanation:
(secA + tanA) (1 − sinA)
= `(1/cosA+sinA/cosA)(1-sinA)`
= `((1+sinA)/cosA)(1-sinA)`
= `(1-sin^2A)/(cosA)`
= `(cos^2A)/cos A`
= cosA
Hence, alternative cosA is correct.
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