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MathsHardMCQ2023 ยท 30 Jan Shift 2

Q70.Let A be a point on the x-axis. Common tangents are drawn from A to the curves x2 + y2 = 8 and y2 = 16x . If one of these tangents touches the two curves at Q and R, then (QR)2 is equal to (1) 64 (2) 76 (3) 81 (4) 72

What This Question Tests

This problem requires finding the common tangent to a circle and a parabola, determining the points of tangency, and then calculating the distance between these points, which is a multi-step process.

Concepts Tested

Equation of tangent to a circleEquation of tangent to a parabolaCondition for tangency (discriminant)Distance between two points

Formulas Used

Tangent to x^2+y^2=r^2: yy1 = x x1 + r^2

Tangent to y^2=4ax: y=mx+a/m

Distance formula

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