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Grade 11Analytical Geometry

The equation of the common tangent to the equal parabola y^2=4ax and x^2=4ay is?

Profile image of Sagar Kumar Patro
10 Years agoGrade 11
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1 Answer

Profile image of Vijay Mukati
10 Years ago
The tangent on y^2 = 4ax will be y = mx + a/m Since this lines touches the x^2 = 4ay.
Therefore replace y here by y = mx + a/m and simplify, You will get the quadratic in x. Now since this touches the parabola, Therfore Put D = 0. fom here you will get m = -1.
Therefore the equation of common tangent will be y = -x -a or x + y+a = 0.
Thanks.