Determine if each of the following statements is true or false.
If it's true, explain why. If it's false, explain why not, or simply
give an example demonstrating why it's false. (A correct choice of
"T/F" with no explanation will not receive any credit.)
(a) If two lines are contained in the same plane, then they must
intersect.
(c) Let n1 and n2 be normal vectors for two planes P1, P2. If n1
and n2 are orthogonal, then the planes P1, P2 intersect in a
line.