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The area of the region bounded by the curves x=at2x = at^2 and y=2aty = 2at between the lines parallel to y−axisy-axis corresponding to t=1t = 1 and t=2t = 2 is equal to :

Solution

✅ Correct Option: 3

Eliminating tt gives the parabola y2=4axy^2 = 4ax, and t=1t=1, t=2t=2 give the ordinates x=ax=a and x=4ax=4a. Using symmetry about the xx-axis, area =2∫a4a2ax dx=8a3(8a3/2−a3/2)=56a23= 2\int_a^{4a} 2\sqrt{ax}\,dx = \frac{8\sqrt{a}}{3}\left(8a^{3/2}-a^{3/2}\right) = \frac{56a^2}{3}.

Note: The two given equations describe one parabola; we have taken the region bounded by the whole curve between the two ordinates.

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