For example pi(r)^2 For the area of a circle and 2(pi)r for the circumference of a circle.
I remember these formulas, but never conceptually grasped why we use a seemingly random number (22/7) and use it in various different formulas for various calculations.
someone ELI5 please.
In: Mathematics
Well pi is not equal to 22/7, that’s just an approximation. Pi is not a rational number, it cannot be written as a ratio of integers (whole numbers).
The reason pi comes up in equations involving circles is because pi is *defined* to be the ratio of the circumference of a circle to its diameter. It may not be obvious, but this ratio is the same for every circle. In other words, if you take any circle, measure the circumference and then measure the diameter, and then divide these two numbers, you will get the number pi every time (assuming that your measurements are perfect and have no error).
So the formula C = 2*pi*r comes right from the definition. And many other quantities involving circles will in some way relate to pi.
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