Page:First six books of the elements of Euclid 1847 Byrne.djvu/44

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BOOK I. PROP. X. PROB.

O bisect a given finite straight line ().

Construct (pr. 1.), draw , making = (pr. 9.).

Then = by (pr. 4.), for = (const.) = and common to the two triangles.

Therefore the given line is bisected.

Q.E.D.