The equation of a circle is
(x-h)² + (y-k)² = r²
for center (h, k) and radius r. Of course, the radius can be computed by putting the point in the equation.
(x-2)² + (y-3)² = (-1-2)² + (1-3)² = 9+4 = 13
The standard equation of the circle is (x-2)² + (y-3)² = 13.
Step 1. Identify the variable.
Step 2. Write an algebraic equation.
Step 3. Solve the equation.
Step 4. Answer the equation.
Step 5. Check answer.
Hope this helps...?
The answer is B.
I timesed 50 by 100 and 1,000. So 5 would be in the thousands place.