原点（圆心）到直线 4x + 3y - 70 = 0 的距离
d = [√( Ax + By + C )" ] / √( A" + B" )
= [√( 4X0 + 3X0 - 70 )" ] / √( 4" + 3" )
= [√( - 70 )" ] / √5"
= 70/5
= 14
圆的半径就是 r = 14
圆就是 x" + y" = 196