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

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  1. Chapter 8 Class 10 Introduction to Trignometry (Term 1)
  2. Serial order wise

Transcript

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 is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.