## Geometry: Common Core (15th Edition)

Use the Segment Addition Postulate to find the value of a. $XY+YZ=XZ$ substitute $a+(a+8)=50$ combine like terms $2a+8=50$ subtract 8 from each side $2a+8-8=50-8$ simplify $2a=42$ divide each side by 2 $2a\div2=42\div2$ $a=21$ Use the value of a to find the segment lengths. $XY=a=21$ $YZ=a+8=21+8=29$