The radius of a circle whose circumference is the sum of that of two circles with radii 36 and 20 units is __.
What is the circumference of a circle with radius 2r units?
Draw a graph for the radius and circumference of the circle using a suitable scale. (Hint: Take radius = 7, 14, 21 units, and so on) From the graph, (a) Find the circumference of the circle when the radius is 42 units. (b) At what radius will the circumference of the circle be 220 units?