This question is similar to Chapter 8 Class 12 Application of Integrals - Examples

Please check the question here 

https://www.teachoo.com/3347/732/Example-3---Find-area-bounded-by-y--x2-and-line-y--4/category/Examples/

 

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Transcript

Question 18 A student observes an open-air Honeybee nest on the branch of a tree, whose plane figure is parabolic shape given by 𝑥^2=4𝑦. Then the area (in sq units) of the region bounded by parabola 𝑥^2=4𝑦 and the line 𝑦=4 is (A) 32/3 (B) 64/3 (C) 128/3 (D) 256/3Given that y = 4 Let Line AB represent y = 4 Also, Let AOB represent x2 = 4y We have to find area of AOBA Area of AOBA = 2 × Area BONB = 2∫1_𝟎^𝟒▒〖𝒙 𝒅𝒚〗 We know that 𝑥^2= 4𝑦 𝑥 = ± √4𝑦 𝑥 = ± 2√𝑦 Since BONB is in first quadrant we use x = +𝟐√𝒚 Area of AOBA = 2∫1_0^4▒〖𝑥 𝑑𝑦〗 = 2∫1_0^4▒〖2√𝑦 𝑑𝑦〗 = 2 × 2∫1_0^4▒〖〖(𝑦)^(1/2)〗^ 𝑜𝑦〗 = 4 [𝑦^(1/2 + 1)/(1/2 + 1)]_0^4 = 4[𝑦^((1 + 2)/2 )/((1 + 2)/2)]_0^4 = 4[𝑦^(3/2 )/(3/2)]_0^4 = 4 × 2/3 [𝑦^(3/2 ) ]_0^4 = 8/3 〖[(4)〗^(3/2 )−0] = 8/3 [〖(2^2)〗^(3/2 ) ] = 8/3 × 23 = 8/3 × 8 = 𝟔𝟒/𝟑 So, the correct answer is (B)

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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