Core Connections Geometry, 2013
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Core Connections Geometry, 2013 View details
2. Section 6.2
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Exercise 86 Page 380

Practice makes perfect
a Let's highlight the hypothesis and conclusion in the conditional statement.

If the base angles of a triangle are congruent, then it is isosceles. The converse of a conditional statement, q→ p, exchanges the hypothesis and conclusion of the conditional statement. If a triangle is isosceles, then the base angles are congruent. This is true by the Base Angles theorem.

b Like in Part A, we will highlight the hypothesis and conclusion in the conditional statement.

If a figure is a triangle, then the sum of the angles in the figure is $180^(∘)$. Again, to get the converse of the conditional statement, q→ p, we exchange the hypothesis and conclusion. If the sum of the angles in a figure is $180^(∘)$, then the figure is a triangle. To show that the converse is true, consider instead what it would mean to have a sum of 180^(∘). Two angles is not a figure. A quadrilateral's angles sum to 360^(∘). Two angles is too few, and four is too many. Thus, there are three angles in the figure which means it is a triangle. Note that we are assuming that the figure is a polygon.

c Like in Parts A and B, we will highlight the hypothesis and conclusion in the conditional statement.

If I clean my room, then my mom will be happy. Again, to get the converse of the conditional statement, q→ p, we exchange the hypothesis and conclusion. If my mom is happy, then I have cleaned my room. Your mom's happiness is not contingent on whether you cleaned your room or not. Therefore, we conclude that this is not true.