A point C lies between two points A and B such that AC=CB. Prove that AC=AB.
According to question, C lies between points A and B and AC = BC
Adding AC both side we get,
AC + AC = BC + AC
According to definition of Euclid, if equals are added to equals, whole will equal.
Here, (BC + AC) will coincides with AB.
2AC = AB
So, AC = AB