Question

radius = 10.9
diameter =
area =
circumference =

Explanation:

Step1: Recall diameter - radius relation

The diameter $d$ of a circle is twice the radius $r$. So $d = 2r$. Given $r=10.9$ yd, then $d = 2\times10.9=21.8$ yd.

Step2: Recall area formula

The area $A$ of a circle is given by the formula $A=\pi r^{2}$. Substitute $r = 10.9$ yd and $\pi=3.14$. So $A=3.14\times(10.9)^{2}=3.14\times118.81 = 373.0634\approx373.06$ yd².

Step3: Recall circumference formula

The circumference $C$ of a circle is given by the formula $C = 2\pi r$. Substitute $r = 10.9$ yd and $\pi=3.14$. So $C=2\times3.14\times10.9=6.28\times10.9 = 68.452\approx68.45$ yd.

Answer:

Diameter = 21.8 yd
Area = 373.06 yd²
Circumference = 68.45 yd