Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2008/paper-1/6/solution

The point on the parabola is . Implicit differentiation gives , so the tangent line has slope one there. Its perpendicular normal line to a plane curve therefore has slope . The required line is

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