Find the area of the circle and the circumference if the diameter is 10 dm.

Let us denote through the variable R the length of the radius of our circle, through the variable D the length of the diameter of our circle, equal to 10 dm by the condition of our task, through the variable P the number PI equal to 3.14, through the variable L the desired length of our circle and through the variable S the desired area of ​​our circle.

Let’s find the radius of our circle using the following formula.

R = D: 2.

R = 10: 2.

R = 5 dm.

Let’s find the length of our circle using the following formula.

L = 2 x PI x R.

L = 2 x 3.14 x 5.

L = 3.14 x 10.

L = 31.4 dm.

Let’s find the area of ​​our circle using the following formula.

S = PI x R ^ 2.

S = 3.14 x 5 ^ 2.

S = 3.14 x 25.

S = 78.5 dm ^ 2.

Thus, we get that the required length of our circle is 31.4 dm, and the required area of ​​the circle is 78.5 dm ^ 2.