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MathsHardNumerical2021 ยท 27 Aug Shift 1

Q84.If the minimum area of the triangle formed by a tangent to the ellipse x2 = 1 and the co-ordinate axis is + 4a2 b2 kab, then k is equal to ___________.

What This Question Tests

This question requires writing the equation of a tangent to an ellipse, finding its intercepts to form a triangle, and then minimizing the area of this triangle using calculus or algebraic methods.

Concepts Tested

Equation of tangent to an ellipseIntercepts of a line with coordinate axesArea of a triangleMinimization using derivatives or AM-GM inequality

Formulas Used

Tangent to x^2/a^2 + y^2/b^2 = 1 at (x1,y1): xx1/a^2 + yy1/b^2 = 1

Tangent with slope m: y = mx ยฑ โˆš(a^2m^2 + b^2)

Area of triangle with intercepts (X,0) and (0,Y) is 1/2 |X Y|

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