Question

In fig. AC = XD, C is the mid-point of AB and D is the mid-point of XY. Using a Euclid's axiom, show that AB = XY.

Assertion: According to Euclid's 1st axiom- "Things which are equal to the same thing are also equal to one another". Reason: If AB = PQ and PQ = XY, then AB = XY.

The total number of propositions in the Euclid's Elements is

If A, B and C are three points on a line, and B lies between A and C, then prove that AB + BC = AC.