The radius of the circle is 15 cm,
The diameter of the circle is 30 cm,
The circumference of the circle is 94.248 cm,
The area of the circle is 706.86 cm^2
The radius is given in the diagram as half the circle, which is 15 cm.
The diameter is double the radius because the diameter measures the circle from edge to edge, so 15•2=30 cm.
The circumference of the circle is 2•3.14•r=C,
2•3.14=6.28, 6.28•15= 94.248 cm.
The area of the circle is 3.14•r^2, so the radius squared is 225 (15•15) and 225•3.14=706.86 cm squared :)