The point equidistant from the vertices of a triangle is called

The orthocentre of ΔABC is H. The mid-points of AH, BH and CH are respectively x, y and z. Prove that the orthocenter of ΔXYZ is also H.

How will you find the point in side BC of ΔABC which is equidistant from sides AB and AC.

The centroid of a triangle is

The locus of the centre of a circle rolling in a plane is—