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Return to book index Chapter 3 : Perpendicular and Parallel Lines
3.2 Problem Solving Help

Lesson 3.2: Help with Exercises 17-24 on pages 139-140

For Exercise 17, read the paragraph proof several times before you start to fill in the blanks. Then work on each sentence. Note that the information in one part of a sentence is a clue to the information that you must provide in the other part of a sentence.

For Exercise 18, first notice the direction of each arrow so you see how the proof "flows." Fill in the blanks alphabetically (especially c before d). Use Example 2 on page 137 as a good model for a flow proof.

For Exercise 19, remember that the reason given in the right-hand column corresponds to the statement with the same number given in the left-hand column. Also, a statement is based on given information or follows from a previous statement. So, for example, if you are trying to figure out what Statement 5 is, look at both Reason 5 and Statement 4.

For Exercises 20-23, you may find it helpful to look at the flow proof both "forwards" and "backwards." Review previous lessons for ideas that concern complementary angles.

For Exercise 24, sketch the key steps of a proof first, then decide which type of proof you would like to write. If you get stuck using one type, try another type. Your choices include two-column proof, paragraph proof, and flow proof.