Triangle ABC is a right angled triangle, right angled at B. A circle, of radius 4 cm, lies inside the triangle and touches the 3 sides of the triangle. Another circle, with radius 1 cm, lies inside the triangle(but outside the first circle). The second circle touches the first circle and touches the sides AC and BC of the triangle. Find the length of side AB.
If P Q R are three points on a circle, What is the maximum area of the triangle formed by them where radius of circle is a units?