# 1.2 - Use Segments and Congruence 1.2 Use Segments and Congruence Geometry Ms. Rinaldi

Postulate In Geometry, a rule that is accepted without proof is called a postulate or axiom. Postulate 1 The Ruler Postulate EXAMPLE 1 Apply the Ruler Postulate Measure the length of ST to the nearest tenth of a

centimeter. ANSWER The length of ST is about 3.4 centimeters. EXAMPLE 2 Apply the Ruler Postulate

Use a ruler to measure the length of the segment to the nearest 1 inch. 8 a. ANSWER 1 58 in. b. ANSWER 1 3 in. 8

Definition Between Postulate 2 Segment Addition Postulate EXAMPLE 3 Apply the the Segment Addition Postulate

Maps The cities shown on the map lie approximately in a straight line. Use the given distances to find the distance from Lubbock, Texas, to St. Louis, Missouri. SOLUTION Because Tulsa, Oklahoma, lies between Lubbock and St. Louis, you can apply the Segment Addition

Postulate. LS = LT + TS = 380 + 360 = 740 ANSWER The distance from Lubbock to St. Louis is about 740 miles. EXAMPLE 4 Find a length

In Exercises 3 and 4, use the diagram shown. a. Use the Segment Addition Postulate to find XZ. ANSWER 73 b. In the diagram, WY = 30. Can you use the Segment Addition Postulate to find the distance between

points W and Z? Explain your reasoning. ANSWER No; W is not between X and Z. EXAMPLE 5 Find a length Use the diagram to find GH. SOLUTION Use the Segment Addition Postulate to write an

equation. Then solve the equation to find GH. FH = FG + GH Segment Addition Postulate. 36 = 21 + GH Substitute 36 for FH and 21 for FG. 15 = GH

Subtract 21 from each side. EXAMPLE 6 Find a length Use the diagram to find WX. ANSWER 107

Definition Congruent Segments EXAMPLE 7 Compare segments for congruence

Plot J( 3, 4), K(2, 4), L(1, 3), and M(1, 2) in a coordinate plane. Then determine whether JK and LM are congruent. EXAMPLE 8 Compare segments for congruence Plot the points A( 2, 4), B(3, 4), C(0, 2), and D(0, 2) in a coordinate plane. Then determine whether AB and

CD are congruent. Homework Pages 12 13 # 1, 6-14, 20, 21-23