SaiBook.us Geometry

Example

Title: Circumference of a Circle

Grade: 4-a Lesson: S2-L4

Explanation: The best way to understand geometry is by looking at some examples. Take turns and read each example for easy understanding.

Examples:

If the radius of the circle is 45 units, find the circumference of the circle. (Take π = 3.14)

Step 1a

The circle has a radius of 45 units.

$1a$

Explanation: The radius of a circle is 45 units.

Step 1b

Circumference of circle formula = 2πr

Substitute the values C = \$2 \times 3.14 \times 45 \$

C = 282.6 units.

Explanation: Circumference formula: C = 2πr. Calculation: C = \$2 \times 3.14 \times 45 \$ = 282.6 units.

Step 1c

Therefore, the circumference of a circle is 282.6 units.

Explanation: So, the circumference of a circle is 282.6 units.

The circumference of a circle is 16 inches.Find its radius.

Step 2a

The circumference of a circle(c) is given 16 inches.

Now, we have to find the radius of a circle.

$2a$

Explanation: The circle’s circumference is given as 16 inches.

Step 2b

Circumference of circle formula (c) = 2πr

Substitute the values 16 = \$2 \times 3.14 \times r\$

r = \$16/6.28\$

r = 2.54 inches.

Explanation: Circumference of a circle, you’ll need to use the formula C = 2πr.

Once you plug in the values, like 16 = \$2 \times 3.14 \times r\$,

you can solve for r and get the answer of 2.54 inches.

Step 2c

Hence, the radius of a circle is 2.54 inches.

Explanation: Therefore, the radius of a circle is 2.54 inches.