Hi, I've been given the following question for an assignment that carries marks, I've made an attempt and I got some answers, but they don't seem right. Can someone please help me. Thanks!!

(a) A space diagonal of a cube is a line segment joining two diagonally opposite vertices of the

cube in R^3. Find the angle between two space diagonals of a unit cube. - I got 70.53 degrees.

(b) A few years ago it was feared that the Leaning Tower of Pisa was about to collapse. Suppose

two steel cables are attached to the highest point P of the tower (which is 56:5m above ground

level) and anchored to the ground at points 80m East and 20m North of P, and 40m East and

50m North of P respectively, at the same level as the tower's base. What angle do the two cables

make at P? - I got 30 degrees.