Problem 4.1
Answer is at this link.
Problem 4.2
Answer is at this link.
Problem 4.3
Three methods for constructing parallels are explained in the Construction Chapter of B&B, pp. 174-175.
Problem 4.4
Several of these proofs about parallelograms were proved at length in the handout on Suggestions for Proofs and also for Quiz 2 Answers.
Problem 4.5
The solution to this problem was part of the class worksheet on regular pentagons.
Problem 4.6
Answer is at this link.