Question

Need help please on geometry

Answer 1

To solve this we are going to use the formula for the area of a circle: $A= \frac{1}{4} \pi d^2$
where
$A$ is the area of the circle 
$d$ is the diameter of the circle 

We know from our problem that the area of our circle is 10 inches long, so $d=10in$. Lets replace that value in our formula to find $A$:
$A=\frac{1}{4} \pi (10in)^2$
$A=78.54in^2$

We can conclude that the correct answer is: 78.54 square inches, or in centimeters: 506.7 square cm.

Answer 2

The area of a circle is:

A = pi*r^2

given:
d = 10inches
r = 10/2 inches = 5inches

so the are of the given circle is 

A = pi*5^2 = 25pi in.sq

Convert inches to cm;

25pi in.sq ( 127cm / 50 inches )^2 = 161.29pi cm.sq