Use a ruler to find the lengthof the line segmentbelow.Line up the endpointswith numberson your rulerand find the absolutevalueof the differencebetween
thosenumbers.If you measurecorrectly, you will find that this segmentmeasures2.5 inchesor 6.35 cen-
timeters.
SegmentAdditionPostulate
SegmentAdditionPostulate:The measureof any line segmentcan be foundby addingthe measuresof
the smallersegmentsthat compriseit.
That may seemlike a lot of confusingwords,but the logicis quitesimple.In the diagrambelow, if you add
the lengthsof and , you will havefoundthe lengthof. In symbols,.
Use the segmentadditionpostulateto put distancestogether.
Example 4
The map belowshowsthe distancesbetweenthreecollineartowns.Whatis the distancebetweentown1 and town3?You can see that the distancebetweentown1 and town2 is eightmiles.You can also see that the distance
betweentown2 and town3 is five miles.Usingthe segmentadditionpostulate,you can add thesevalues
togetherto find the total distancebetweentown1 and town3.