Question

The equation of a circle is $(x+1{)}^2+(y-4{)}^2=16$. What is its radius?

• A. $16$
• B. $4$
• C. $-4$
• D. $-16$

Answer 1

Answer: (B)

$4$

Compare the equation with the standard form with center at (h, k) and radius, r is: $(x-h{)}^2+(y-k{)}^2=r^2$
$(x+1{)}^2+(y-4{)}^2=16$
So, $r^2=16$
Taking root on both the sides, we get
$r=4$