Question

If you know the diameter of a circle,

how do you find the following. Explain
the steps clearly
a. the area of that circle?
b. the circumference of the circle?

Answer 1

Explanation:

a. Area of a circle = πr², where r means radius.

Step 1: converted diameter to radius.

diameter = 2 radius

In other way of writing, radius =
`(1)/(2)` diameter.

Step 2: substitute radius into the formula.

Area of a circle = π(
`(1)/(2)`d)²

Step 3: substitute π into the formula.

some question is given the value of π), if not substitute 3.14 for π.

Area of a circle = 3.14(
`(1)/(2)`d)²

Step 4: substitute d into the formula, then we can solve its area.

b. a. Circumference of a circle = 2πr, where r means radius.

Step 1: converted diameter to radius.

diameter = 2 radius

In other way of writing, radius =
`(1)/(2)` diameter.

Step 2: substitute radius into the formula.

C = 2π(
`(1)/(2)`d)

Step 3: substitute π into the formula.

some question is given the value of π), if not substitute 3.14 for π.

C = 2(3.14)(
`(1)/(2)`d)

Step 4: substitute d into the formula, then we can solve its circumference.