- Additionpropertyof equality
Can you see why we wrotethe proportionthis way, ratherthan as , whichis
also a true proportion?
It’s because , but thereis no similarway to simplify.
Note:The converseof this theoremis also true.If a line dividestwo sidesof a triangleinto proportional
segments,then the line is parallelto the third side of the triangle.
Example 2
In the diagrambelow,.Whatis an expressionin termsof for the lengthof?Accordingto the TriangleProportionalityTheorem,Thereare somevery interestingcorollariesto the TriangleProportionalityTheorem.One couldbe called
theLinedNotebookPaperCorollary!
ParallelLinesand Transversals
Example 3