[tex]\pi-\bold{pi}\\\\\pi\ \text{it's the ratio of a circle's circumference to its diameter}\\\\\pi=\dfrac{\text{circumference of a circle}}{\text{circle diameter}}\\\\\pi\ \text{it's irrarional number}\\\\\pi=3.14159265358979323846264338327...\\\\\text{Approximation of}\ \pi:\\\\\pi\approx3.14\\\\\pi\approx\dfrac{22}{7}\\\\\pi\approx\dfrac{355}{113}[/tex]
The number pi occurs when calculating the surface area or volume of the rotational solids.
Cylinder:
[tex]S.A.=2\pi r^2+2\pi rH\\\\V=\pi r^2H[/tex]
Cone:
[tex]S.A.=\pi r^2+\pi rl\\\\V=\dfrac{1}{3}\pi r^2H[/tex]
Sphere:
[tex]S.A.=4\pi R^2\\\\V=\dfrac{4}{3}\pi R^3[/tex]
The number pi occurs when calculating the area and the circumference of a circle.
[tex]C=\pi d=2\pi r\\\\A=\pi r^2[/tex]
It is also used to convert angle measure in degrees to radians.
[tex]x^o=\dfrac{x\pi}{180}\ rad[/tex]
