Prove the following indirectly using two-column form:

Question

Given: ∆WSO and ∆LSO are equilateral

∆WSL is not equilateral

Prove: ∆WOL is not equilateral

Answer 1

Suppose triangle WOL is equailateral.

WO = OL = WL : Def of equilateral.

WSO and LSO are equilateral : given

WS=SO=WO and LS=SO=OL : def of equilateral

LS=SL : reflexive

WS=SO= WO = LS=SL=OL=WL=WO : substitution/transitive

traingle WSL is equilateral : def of equilateral

contradiction