Why is pi equal to 3. 14

Q. Find the circumference of a circle whose radius is equal to $15\text{cm}$. Use $\pi =3.14$.

Q. The circumference of a circle is approximately equal to $157units$. Taking the value of $\pi =3.14$, what is the radius of the circle?

Q. The value of $\frac{\pi }{53.2}$ with due regard to significant figures is (Use $\pi =3.14$) :

Q. Why we discovered pi in maths as we know that it's value is 3.14............. Instead we can have any other value of it like 6 or 91 It would make easy. And why there are too much digit because we only use 3.14

Q. In the following figure find the area of the shaded region. (Use π = 3.14)