1. EXAMPLE 3 Find a length Use the diagram to find GH. Use the Segment Addition Postulate to write an equation. Then solve the equation to find GH. SOLUTION Segment Addition Postulate. Substitute 36 for FH and 21 for FG. Subtract 21 from each side. 21 + GH = 36 FG + GH=FH = 15GH

2. EXAMPLE 4 Compare segments for congruence SOLUTION 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. To find the length of a horizontal segment, find the absolute value of the difference of the x -coordinates of the endpoints. Use Ruler Postulate. JK = 2 – (– 3) = 5

3. EXAMPLE 4 Compare segments for congruence To find the length of a vertical segment, find the absolute value of the difference of the y -coordinates of the endpoints. Use Ruler Postulate. LM = – 2 – 3 = 5 JK and LM have the same length. So, JK LM. = ~ ANSWER

4. GUIDED PRACTICE for Examples 3 and 4 Use the segment addition postulate to write an equation. Then solve the equation to find WX Use the diagram at the right to find WX. 5. vx = vw + wx 144= 37 + wx 107 = wx Segment addition postulate Subtract 37 from each side SOLUTION ANSWER WX = 107 Substitute 37 for vw and 144 for vx

5. GUIDED PRACTICE for Examples 3 and 4 6. 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. Length of AB is not equal to the length of CD, so they are not congruent ANSWER