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Ex 8.4, 4 - Chapter 8 Class 10 Introduction to Trignometry - Part 4

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x 8.4, 4 Choose the correct option. Justify your choice. (iii) (sec A + tan A) (1 – sin A) sec A (B) sin A (C) cosec A (D) cos A (sec A + tan A) (1 – sin A) = (1/(π‘π‘œπ‘  𝐴)+sin⁑𝐴/cos⁑〖 𝐴〗 ) (1 βˆ’sin⁑〖 𝐴)γ€— = ((1+ sin⁑〖 𝐴)γ€—)/cos⁑〖 𝐴〗 Γ—(1 βˆ’sin⁑〖 𝐴)γ€— = ((1+ sin⁑〖 𝐴)(1 βˆ’γ€– sin〗⁑〖 𝐴)γ€— γ€—)/cos⁑〖 𝐴〗 = ((1^2 βˆ’γ€– sin2〗⁑〖 𝐴)γ€—)/cos⁑〖 𝐴〗 = ((1 βˆ’γ€– sin2〗⁑〖 𝐴)γ€—)/cos⁑〖 𝐴〗 = (π‘π‘œπ‘ 2 𝐴)/cos⁑〖 𝐴〗 = cos A Hence, (D) is the correct answer

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.