Areas related to circle

For a circle with radius = $\text{r}$,

Circumference $\text{= 2πr}$

Area ${\text{= πr}}^{\text{2}}$

$\text{Π = 3}\text{.14 or }\frac{\text{22}}{\text{7}}$

Area of semicircle $\text{= }\frac{{\text{πr}}^{\text{2}}}{\text{2}}$

Area of sector:

If angle of arc $\text{AB}$ with centre is $\text{θ}$

Area of minor sector $\text{= }\frac{\text{θ}}{\text{360}}{\text{ × πr}}^{\text{2}}$

Area of major sector $\text{=}$ A(circle) $-$ A(minor

sector)

${\text{= πr}}^{\text{2}}\text{ - }\frac{\text{θ}}{\text{360}}{\text{ × πr}}^{\text{2}}$

Length of arc $\text{= }\frac{\text{θ}}{\text{360}}\text{ × 2πr}$

Area of segment

Area of segment AB $\text{=}$ A(sector) $-$ A (triangle)

$\text{= A}\left(\text{0 - AB}\right)\text{ - A}\left(\Delta \text{OAB}\right)$