Answer:

Step-by-step explanation:
<u><em>Given equation is</em></u>

Adding 42 to both sides

Completing squares

Adding (3)² => 9 and (3)² => 9 to both sides

Comparing it with
where Center = (h,k) and Radius = r
We get:
Center = (3,3)
Radius = 
Here's a pattern to consider:
1+100=101
2+99=101
3+98=101
4+97=101
5+96=101
.....
This question relates to the discovery of Gauss, a mathematician. He found out that if you split 100 from 1-50 and 51-100, you could add them from each end to get a sum of 101. As there are 50 sets of addition, then the total is 50×101=5050
So, the sum of the first 100 positive integers is 5050.
Quick note
We can use a formula to find out the sum of an arithmetic series:

Where s is the sum of the series and n is the number of terms in the series. It works for the above problem.
Hydrosphere
hydro means water
We have the area of the base of a triangular prism= a*b
the volume of triangular prism =a*b*c( where c is the height) so that 210=a*b*14 ==> 210= base area*14==> base area= 210/14