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That a Scalenum, and an Isosceles, be all one.
Let ABC be a Scalenum; The same ABC is also an Isosceles. For fill the whole Area ABC with Lines par∣rallell to AC by the 3. Axiom. There is then as many points in BA as in BC by the 1. Axiom; and therefore by the second, BA is equall to BC. and consequently by the 1. Definition. ABC is an Isosceles.