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← JEE Main 2022 · 25 Jul · Shift 1
MathematicsInteger+4 / -1Question 29 of 90

JEE Main 2022 · 25 Jul · Shift 1, Mathematics question 29

The sum of diameters of the circles that touch (i) the parabola 75x2=64(5y−3)75x^2=64(5y-3) at the point (85,65)\left(\dfrac85,\dfrac65\right) and (ii) the yy-axis, is equal to ______.

Answer and worked solution

Official answer: 10

Normal at (85,65)\left(\frac85,\frac65\right) has slope −43-\frac43. Centres on it with radius equal to ∣x∣|x| give radii 1 and 4.

Diameters 2+8=102+8=10.

Answer: 10