Find the angle where two parabolas intersect

Given two parabolic functions, find the angles where the curves intersect. Calculus Made Easy, Ch. 10, Geometrical Meaning of Differentiation. (p 89, Question 8). I've gone full Khan Academy on this one. No fancy swooshes. No online graphing calculators. Just you, me and an online whiteboard. ... https://www.youtube.com/watch?v=1VNh9g_lH0k