Question

If the sides of a triangle measure 72,75 and 21, what is the measure of its inradius

Answer 1

• The sides of the triangle happen to be a Pythagorean triplet.
  Hence, the triangle is a right angled triangle.
  
  For a right angled triangle,
  The measure of in radius = (product of perpendicular sides) / (perimeter of triangle)
  
  = (72 * 21) / (72 + 21 +75) = 1512 / 168 = 9