d)
[tex]x^2+y^2-20y+36=0\\x^2+\underbrace{y^2-20y+100}_{=(y-10)^2}-100+36=0\\x^2+(y-10)^2-64=0\\x^2+(y-10)^2=64\\S=(0,10)\quad r=\sqrt{64}=8[/tex]
e)
[tex]x^2+y^2+10x-2y+10=0\\\underbrace{x^2+10x+25}_{=(x+5)^2}-25+\underbrace{y^2-2y+1}_{=(y-1)^2}-1+10=0\\(x+5)^2+(y-1)^2-16=0\\(x+5)^2+(y-1)^2=16\\S=(-5,1)\quad r=\sqrt{16}=4[/tex]
