Circumference and Area of Circles

The area (A) of a circle is calculated using the formula: A = $$\text{π}r^2$$ , where r is the radius.

The circumference (C) of a circle is calculated using the formula: C = $$2\text{π}r$$ or C = $$\text{π}d$$ , where d is the diameter.

π (pi) is approximately equal to 3.14.

The area is A = $$\text{π}(7)^2$$ = 153.94 cm².

The circumference is C = $$\text{π}(10)$$ = 31.42 m.

The diameter (d) of a circle is twice the radius (r): d = 2r.

To convert diameter to radius, divide the diameter by 2: r = $$\frac{d}{2}$$ .

The area is A = $$\text{π}(5)^2$$ = 78.54 in².

The circumference is C = $$2\text{π}(3)$$ = 18.85 ft.

To find the radius, use the formula: r = $$\text{√}\frac{A}{\text{π}}$$ . For A = 50 cm², r ≈ 3.99 cm.