The size of a circle changes a lot when we change its radius.

Here are the important formulas to remember:

• Circumference: ( C = 2\pi r )
• Area: ( A = \pi r^2 )

How Changing the Radius Affects a Circle

1. Circumference:

   • If we make the radius (( r )) bigger, the circumference also gets bigger in a straight line.
   • For a radius of 1 unit, the circumference is about ( 2\pi ) or around 6.28 units.
   • If we double the radius to 2 units, the circumference becomes ( 4\pi ), which is about 12.57 units.

2. Area:

   • The area increases much faster than the circumference.
   • For a radius of 1 unit, the area is about ( \pi ) or 3.14 square units.
   • If we double the radius to 2 units, the area jumps to ( 4\pi ), which is about 12.57 square units.

This shows how changing the radius can really change the size and shape of a circle!