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← JEE Main 2022 · 25 Jul · Shift 1
MathematicsSingle correct+4 / -1Question 13 of 90

JEE Main 2022 · 25 Jul · Shift 1, Mathematics question 13

Let the locus of the centre (α,β)(\alpha,\beta), β>0\beta>0, of the circle which touches the circle x2+(y−1)2=1x^2+(y-1)^2=1 externally and also touches the xx-axis be L. Then the area bounded by L and the line y=4y=4 is :

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Answer and worked solution

Official answer: C

Locus. α2+(β−1)2=(β+1)2\alpha^2+(\beta-1)^2=(\beta+1)^2, i.e. x2=4yx^2=4y.

Area with y=4y=4: 2∫04(4−x24)dx=6432\displaystyle\int_0^4\left(4-\frac{x^2}4\right)dx=\frac{64}3.

(C)