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Some Applications Of Trigonometry

Question
CBSEENMA10008270

Prove the following identity:
cotθ minus tanθ space equals space fraction numerator 2 space cos squared straight theta minus 1 over denominator sinθ minus cosθ end fraction.







Solution
cot space straight theta space minus space tanθ space equals space fraction numerator 2 space cos squared straight theta minus 1 over denominator sinθ. space cosθ end fraction
L.H.S. = cot space straight theta space minus space tanθ
equals space cosθ over sinθ minus sinθ over cosθ equals fraction numerator cos squared straight theta minus sin squared straight theta over denominator sinθ. space cosθ end fraction
equals space fraction numerator cos squared straight theta minus left parenthesis 1 minus cos squared straight theta right parenthesis over denominator sinθ. space cosθ end fraction space equals space fraction numerator cos squared straight theta minus 1 plus cos squared straight theta over denominator sinθ. space cosθ end fraction
equals space fraction numerator 2 space cos squared straight theta minus 1 over denominator sinθ. space cosθ end fraction space equals space straight R. straight H. straight S.
Hence, L.H.S. = R.H.S.

Some More Questions From Some Applications of Trigonometry Chapter

In ΔABC, right angled at B. AB = 24 cm, BC = 7 cm. Determine:
(i) sin A cos A,
(ii) sin C, cos C.