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In general, three normals can be drawn through a point in the plane of a parabola to the curve. |
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Answer» Let P(h, k) be a point in the plane of y2 = 4ax. It is known that the normal to parabola at (at2, 2at) is tx + y = 2at + at3. This normal passes through P(h,k th + k = 2at + 2at + at3 at3 + (2a - h)t - k = 0 .....(1) Equation (1) is a cubic equation in t and hence, in general, it has three roots and hence, there are three points on the curve at which normals drawn to the parabola are concurrent at P(h, k). |
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