Coordinate Geometry - Equation of a Straight Line

A robot follows a closed route around a seven-sided platform. Its turning points, in order, are
\[P(-3,0),\ Q(-3,3),\ R(-1,5),\ S(2,5),\ T(4,3),\ U(4,0),\ V(0,-2).\] It returns directly from \(V\) to \(P\).

1. Find the sum of the platform’s interior angles.

   [2]

2. A vertical safety barrier follows the line \(x=-3\). Which segment of the route runs along this barrier?

   [1]

3. A sensor beam follows the line \(y=-x+7\). Which segment of the route lies along this beam?

   [1]