Check sibling questions

 


Transcript

Example 25 Evaluate the following integrals: (iv) ∫_0^(πœ‹/4)β–’γ€–sin^3⁑2𝑑 cos⁑2 𝑑〗 𝑑𝑑 Let F(π‘₯)=∫1▒〖𝑠𝑖𝑛^3 2𝑑 π‘π‘œπ‘  2𝑑 𝑑𝑑〗 Let s𝑖𝑛 2𝑑=𝑒 Differentiating w.r.t.π‘₯ (𝑑(sin⁑2𝑑))/𝑑𝑑=𝑑𝑒/𝑑𝑑 2cπ‘œπ‘  2𝑑 =𝑑𝑒/𝑑𝑑 𝑑𝑑=𝑑𝑒/(2 π‘π‘œπ‘  2𝑑) Putting value of u and du in our integral ∫1▒〖𝑠𝑖𝑛^3 2𝑑 π‘π‘œπ‘  2𝑑 𝑑𝑑〗=∫1▒〖𝑒^3 π‘π‘œπ‘  2𝑑 Γ— 𝑑𝑒/(2 π‘π‘œπ‘  2𝑑)γ€— =1/2 ∫1▒〖𝑒^3 𝑑𝑒〗 =1/2 𝑒^(3+1)/(3+1)=1/2 𝑒^4/4= 𝑒^4/8 Putting back 𝑒=𝑠𝑖𝑛 2𝑑 =1/8 𝑠𝑖𝑛^4 2𝑑 Hence, F(𝑑)=1/8 𝑠𝑖𝑛^4 2𝑑 Now, ∫_0^(πœ‹/4)▒〖𝑠𝑖𝑛^3 2𝑑 π‘π‘œπ‘  2𝑑=𝐹(πœ‹/4)βˆ’πΉ(0) γ€— =1/8 𝑠𝑖𝑛^4 2(πœ‹/4)βˆ’1/8 𝑠𝑖𝑛^4 2(0) =1/8 𝑠𝑖𝑛^4 πœ‹/2βˆ’1/8 𝑠𝑖𝑛^4 (0) =1/8 Γ—1^4βˆ’1/8 Γ—0^4 =1/8 Γ—1βˆ’0 =𝟏/πŸ–

  1. Chapter 7 Class 12 Integrals
  2. Serial order wise

About the Author

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo