MathDB
Today's calculation of Integral 781

Source: 2012 Sophia University entrance exam/Management

February 9, 2012
calculusintegrationconicsparabolaanalytic geometrygraphing linesslope

Problem Statement

Let l, ml,\ m be the tangent lines passing through the point A(a, a1)A(a,\ a-1) on the line y=x1y=x-1 and touch the parabola y=x2y=x^2. Note that the slope of ll is greater than that of mm.
(1) Exress the slope of ll in terms of aa.
(2) Denote P, QP,\ Q be the points of tangency of the lines l, ml,\ m and the parabola y=x2y=x^2. Find the minimum area of the part bounded by the line segment PQPQ and the parabola y=x2y=x^2.
(3) Find the minimum distance between the parabola y=x2y=x^2 and the line y=x1y=x-1.