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Some Applications Of Trigonometry

Question
CBSEENMA10007728

Choose the correct option and Justify your choice.
(sec A + tan A) (1 - sin A) = 
(A) sec A    (B) sin A    (C) cosec A       (D) cos A


Solution
space left parenthesis Sec space straight A plus space tan space straight A right parenthesis space left parenthesis 1 minus sinA right parenthesis
space space space space space space space space space space space space space space space space space equals space open parentheses 1 over cosA plus sinA over cosA close parentheses space left parenthesis 1 minus sinA right parenthesis
space space space space space space space space space space space space space space space space space equals space fraction numerator left parenthesis 1 plus sinA right parenthesis space over denominator cos space straight A end fraction left parenthesis 1 minus sinA right parenthesis
space space space space space space space space space space space space space space space space space space equals space fraction numerator 1 minus sin squared straight A over denominator cosA end fraction space equals space fraction numerator cos squared straight A over denominator cos space straight A end fraction equals space cosA
Hence, correct option is (D)