The radii of two circles are 8cm and 6cm respectively. Find the radius of the circle having its area equal to the sum of the areas of the two circles.

If a square is inscribed in a circle, find the ratio of the areas of the circle and the square.

A park is in the form of a rectangle 120m×100m. At the centre of the park there is a circular lawn. The area of park excluding lawn is 8700m². Find the radius of the circular lawn.

The radii of two circles are 19cm and 9cm respectively. Find the radius and area of the circle which has its circumference equal to the sum of the circumferences of the two circles..

A car travels 1 kilo meter distance in which each wheel makes 450 complete revolutions. Find the radius of its wheels.