50*90=3.14r^2

Solution for 50*90=3.14r^2 equation:

50*90=3.14r^2

We move all terms to the left:

50*90-(3.14r^2)=0

We add all the numbers together, and all the variables

-(3.14r^2)+4500=0

We get rid of parentheses

-3.14r^2+4500=0

a = -3.14; b = 0; c = +4500;
Δ = b2-4ac
Δ = 02-4·(-3.14)·4500
Δ = 56520
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{56520}=\sqrt{36*1570}=\sqrt{36}*\sqrt{1570}=6\sqrt{1570}$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{1570}}{2*-3.14}=\frac{0-6\sqrt{1570}}{-6.28}
=-\frac{6\sqrt{1570}}{-6.28}
=-\frac{\sqrt{1570}}{-1.0466666666667}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{1570}}{2*-3.14}=\frac{0+6\sqrt{1570}}{-6.28}
=\frac{6\sqrt{1570}}{-6.28}
=\frac{\sqrt{1570}}{-1.0466666666667}
$