Since you already know the radius multiply it by itself(20*20=400)then multiply that amount by 3.14.(formula: 3.14*(radius*radius)
Here you go!! It would be, 6-3+52!
I think 60-79 or 60-69 and 70-79
Let the number of rows be = r
Let the number of seats per row be = s
we know that the number of seats is 126.
So,
..... (1)
As given, there are five more seats per row than the number of rows, so we can say that:
![s=r+5](https://tex.z-dn.net/?f=s%3Dr%2B5)
Putting this in equation (1)
![(r+5)*r=126](https://tex.z-dn.net/?f=%28r%2B5%29%2Ar%3D126)
![r^{2}+5r=126](https://tex.z-dn.net/?f=r%5E%7B2%7D%2B5r%3D126)
![r^{2}+5r-126=0](https://tex.z-dn.net/?f=r%5E%7B2%7D%2B5r-126%3D0)
![r^{2}+14r-9r-126=0](https://tex.z-dn.net/?f=r%5E%7B2%7D%2B14r-9r-126%3D0)
![(r+14)(r-9)=0](https://tex.z-dn.net/?f=%28r%2B14%29%28r-9%29%3D0)
r=-14 and r=9 (neglecting the negative value) we get r=9
And s=r+5
so, s =9+5=14
Hence, there are 5 rows and 14 seats per row.