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Some Applications Of Trigonometry

Question
CBSEENMA10008268

Prove the following identity:
left parenthesis 1 plus tan squared straight theta right parenthesis plus open parentheses 1 plus fraction numerator 1 over denominator tan squared straight theta end fraction close parentheses space equals fraction numerator 1 over denominator sin squared straight theta minus sin to the power of 4 straight theta end fraction




Solution

L.H.S. = left parenthesis 1 plus tan squared straight theta right parenthesis plus open parentheses 1 plus fraction numerator 1 over denominator tan squared straight theta end fraction close parentheses
            equals space left parenthesis 1 plus tan squared straight theta right parenthesis space plus space left parenthesis 1 plus cot squared straight theta right parenthesis
space equals sec squared straight theta space plus space cosec squared straight theta
space equals space fraction numerator 1 over denominator cos squared straight theta end fraction plus fraction numerator 1 over denominator sin squared straight theta end fraction space equals space fraction numerator sin squared straight theta plus cos squared straight theta over denominator cos squared straight theta. space sin squared straight theta end fraction
equals space fraction numerator sin squared straight theta plus cos squared straight theta over denominator left parenthesis 1 minus sin squared straight theta right parenthesis space sin squared straight theta end fraction space equals space fraction numerator 1 over denominator sin squared straight theta minus sin to the power of 4 straight theta end fraction equals straight R. straight H. straight S.
Hence, L.H.S. = R.H.S.