Given a radius
, the volume of a sphere is given by

We can solve this formula for the radius, given the volume:
![r=\sqrt[3]{\dfrac{3V}{4\pi}}](https://tex.z-dn.net/?f=r%3D%5Csqrt%5B3%5D%7B%5Cdfrac%7B3V%7D%7B4%5Cpi%7D%7D)
We can plug our value for the volume to get the radius:
![r=\sqrt[3]{\dfrac{3\cdot 12\pi}{4\pi}}=\sqrt[3]{9}](https://tex.z-dn.net/?f=r%3D%5Csqrt%5B3%5D%7B%5Cdfrac%7B3%5Ccdot%2012%5Cpi%7D%7B4%5Cpi%7D%7D%3D%5Csqrt%5B3%5D%7B9%7D)
The common factors are -
-1
-2
-4
^^^^^Simplify
Estimate
Step 1: Estimate the square root of 2:
1.4x1.4=1.96
1.41x1.41=1.9881
1.42x1.42=2.0164
1.9881 is closer to 2 than 2.0164
Square root of 2 is about 1.41
Step 2: Multiply the answer in step 1 by 8
1.41x8=11.28
8 times square of 2 is about 11.28
Square root of 128 is about 11.28
If you put square root of 128 in a calculator it would say 11.31 something...
232.5 (Triangle)
+320. (Rectangle)
=------------
342.5 (area)