Question

Find the radius of the circle whose equation is $x^2+y^2-6x+8y=0$

• A. 1
• B. 2
• C. 3
• D. 4
• E. 5

Answer 1

The correct option is E 5

Given, $x^2+y^2-6x+8y=0$
$\Rightarrow x^2+y^2-2\left(3\right)\left(x\right)+2\left(4\right)\left(y\right)+9+16=25$
$\Rightarrow {(x-3)}^2+{(y+4)}^2=5^2$

Comparing with $(x-h{)}^2+(y-k{)}^2=r^2$
Therefore, the radius of circle is $5$.