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MathsHardMulti concept2015 · 10 Apr Online

Q71.Let the tangents drawn to the circle, x2 + y2 = 16 from the point P(0, h) meet the x -axis at points A and B . If the area of ΔAPB is minimum, then positive value of h is: (1) 4√2 (2) 3√2 (3) 4√3 (4) 3√3

What This Question Tests

This question combines finding the equation of tangents to a circle, calculating the area of a triangle formed by these tangents and the x-axis, and then using calculus to minimize this area.

Concepts Tested

Equation of tangent from an external pointArea of a triangleApplications of derivatives for optimization

Formulas Used

Equation of tangent to x²+y²=r² from (x1, y1) is x*x1+y*y1=r²

Area of triangle = 1/2 * base * height

Differentiation for minimization

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