McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
3. Inequalities in One Triangle
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Exercise 30 Page 431

Use the theorem regarding Angle-Side Relationships in Triangles to compare the lengths of the sides opposite to the angles.

m∠ ABD > m∠ BDA

Practice makes perfect

In this exercise we are asked to use the given figure to determine the relationship between ∠ ABD and ∠ BDA. Let's consider the given diagram. We will mark the angles we are interested in.

In order to compare the angles, we are going to use Theorem 5.9 about Angle-Side Relationships in Triangles.

Angle-Side Relationships in Triangles

If one side of a triangle is longer than another side, then the angle opposite the longer side has greater measure than the angle opposite the shorter side.

From the diagram, we can see that ∠ ABD is opposite to side AD and ∠ BDA is opposite to side AB. Note that we are given the measurements for these segment lengths. Let's compare them. AD&=13 AB&=3 We know that AD is longer than AB. Therefore, from the theorem about the Angle-Side Relationships in Triangles we can conclude that m∠ ABD is greater than m∠ BDA.