radius

diameter

area

itself

radius

diameter

circumference

itself

π

Σ

Ψ

⊈

Pi

Omega

Alpha

Sigma

pi

beta

alpha

sigma

$$\frac{C}{6.5}$$

$$\frac{6.5}{C}$$

$$\frac{C}{13}$$

$$\frac{13}{C}$$

$$\frac{43.96}{7}$$

$$\frac{43.96}{14}$$

$$\frac{7}{43.96}$$

$$\frac{14}{43.96}$$

3.14

314

3.41

31.519875

77.9 / 24.8

24.8 / 77.9

Multiply C x π

Divide C / π

3.11

3.14

4.13

6.28

Area

Diameter

Circumference

Chord

The area of a circle is equal to pi times the radius squared

The circumference of a circle is equal to the pi times the diameter.

The circumference of a circle is equal to pi times the radius squared

The area of a circle is equal to pi times the diameter

28.26 ft²

28.26 ft

28.26

56.52 ft

37.68 m²

37.68 m

18.84 m

18.84 m²

87.92 cm

43.96 cm

21.98 cm

3.14 cm

40.69 yd

5.65 yd

11.30 yd

22.61 yd

14.13 km

56.52 km

28.26 km

63.59 km

They both solve for circumference. In the first formula it uses diameter, in the second formula it uses two times the radius, which is the same thing as diameter.

They both solve for circumference, in the first uses diameter and the second uses pi.

They both solve for area. In the first formula it uses diameter, in the second formula it uses two times the radius, which is the same thing as diameter.

They both use circumference to solve for pi. One uses radius, the other uses diameter.