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Example 36 - Find dy/dx, if  x = a (theta + sin theta), y = a

Example 36 - Chapter 5 Class 12 Continuity and Differentiability - Part 2
Example 36 - Chapter 5 Class 12 Continuity and Differentiability - Part 3

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Transcript

Example 36 Find 𝑑𝑦/𝑑π‘₯ , if π‘₯ = π‘Ž (πœƒ+sinβ‘πœƒ), 𝑦 = π‘Ž (1 – cosβ‘πœƒ) 𝑑𝑦/𝑑π‘₯ = 𝑑𝑦/𝑑π‘₯ Γ— π‘‘πœƒ/π‘‘πœƒ 𝑑𝑦/𝑑π‘₯ = 𝑑𝑦/π‘‘πœƒ Γ— π‘‘πœƒ/𝑑π‘₯ 𝑑𝑦/𝑑π‘₯ = (𝑑𝑦/π‘‘πœƒ)/(𝑑π‘₯/π‘‘πœƒ) Calculating π’…π’š/π’…πœ½ 𝑦 = π‘Ž (1 – cosβ‘πœƒ) 𝑑𝑦/π‘‘πœƒ = 𝑑(π‘Ž (1 – cosβ‘πœƒ))/π‘‘πœƒ 𝑑𝑦/π‘‘πœƒ = π‘Ž (0 βˆ’(βˆ’sinβ‘πœƒ )) 𝑑𝑦/π‘‘πœƒ = 𝒂 (π’”π’Šπ’β‘πœ½ ) Calculating 𝒅𝒙/π’…πœ½ π‘₯ = π‘Ž (πœƒ+π‘ π‘–π‘›β‘πœƒ) 𝑑π‘₯/π‘‘πœƒ = 𝑑(π‘Ž(πœƒ + π‘ π‘–π‘›β‘πœƒ))/π‘‘πœƒ 𝑑π‘₯/π‘‘πœƒ = π‘Ž (π‘‘πœƒ/π‘‘πœƒ+𝑑(sinβ‘πœƒ )/(π‘‘πœƒ )) 𝑑π‘₯/π‘‘πœƒ = 𝒂 (𝟏+𝐜𝐨𝐬⁑𝜽 ) Therefore 𝑑𝑦/𝑑π‘₯ = (𝑑𝑦/π‘‘πœƒ)/(𝑑π‘₯/π‘‘πœƒ) 𝑑𝑦/𝑑π‘₯ = π‘Ž" " (sinβ‘πœƒ )/π‘Ž" " (1 +γ€– cosγ€—β‘πœƒ ) 𝑑𝑦/𝑑π‘₯ = sinβ‘πœƒ/(1 +γ€– cosγ€—β‘πœƒ ) 𝑑𝑦/𝑑π‘₯ = (γ€–πŸ π’”π’Šπ’γ€—β‘γ€– 𝜽/πŸγ€— .γ€– 𝒄𝒐𝒔〗⁑〖 𝜽/πŸγ€—)/(1 + γ€–πŸ 〖𝒄𝒐𝒔〗^𝟐 γ€—β‘γ€–πœ½/πŸγ€— βˆ’ 𝟏) 𝑑𝑦/𝑑π‘₯ = (γ€–2 sin〗⁑〖 πœƒ/2γ€— .γ€– cos〗⁑〖 πœƒ/2γ€—)/γ€–2 cos^2 γ€—β‘γ€–πœƒ/2γ€— 𝑑𝑦/𝑑π‘₯ = (sin⁑〖 πœƒ/2γ€— )/γ€–cos γ€—β‘γ€–πœƒ/2γ€— π’…π’š/𝒅𝒙 = π­πšπ§β‘γ€–πœ½/πŸγ€— Rough We know that sin 2ΞΈ = 2 sin ΞΈ cos ΞΈ Replacing ΞΈ by πœƒ/2 sin ΞΈ = 2 π’”π’Šπ’β‘γ€–πœ½/πŸγ€— π’„π’π’”β‘γ€–πœ½/πŸγ€— and cos 2ΞΈ = 2cos2 ΞΈ – 1 Replacing ΞΈ by πœƒ/2 cos ΞΈ = 2cos2 𝜽/𝟐 – 1

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Davneet Singh

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.