Question 6
ABC is a right-angled triangle and O is the mid-point of the side opposite to the right angle. Explain why O is equidistant from A, B and C. ( The dotted lines are drawn additionally to help you.)
The two right triangles △ABC and △ACD make a rectangle ABCD.
AC and BD are diagonals of the rectangle, so they are equal in length, and also bisect each other.
So, O is the equidistant from A, B, C and D.