When two curves intersect in a plane, the angle between them is dened to be the angle made by their respective tangent lines, drawn at the point of intersection. Suppose the curves cl and (:2 have tangent lines l1 and l2, respectively, with corresponding slopes m1 and pm. If a is the measure of the positive angle from (:1 to (:2, then it follows from your precalculus that m2 m1 tano: = 1+m1m2 A curve which cuts every member of a given 1parameter family of curves in the same angle is called an isogonal trajectory of the family. Let 'H be the family of curves y2 + 2mg m2 = k. Find a 1-parameter family of isogonal trajectories to 'H, where the angle of intersection is a = 7r/4