+868 For what value of $c$ will the circle with equation $x^2 - 10x + y^2 + 10y + c = 0$ have a radius of length 1?
+37147 Arrange into standard circle equation form by completing the squares for x and y
x^2 - 10x + 25 + y^2 + 10y + 25 = 25 +25 -c
(x-5)^2 + ( y+5)^2 = 50 - c 50 - c = radius ^2
50 - c = 1^2
-c = -49 So C = 49
