Multivariable Calculus HOMEWORK Problem 1.1: a) Check that A = (3, 4,5), B = (3,2,3), C = (1, 4, 3), D = (1, 2, 5) define the corners of an regular tetrahedron. b) Find the center and radius of the smallest sphere through all four points. Problem 1.2: Draw the tilted frustrum (x] + ly| + |=|