Question

The circle below is centered at the origin and has a radius of 7. What is its equation?

Answer 1

Answer:

$x^2 + y^2 = 49$

Step-by-step explanation:

Since, the equation of a circle is,

$(x-h)^2 + (y-k)^2 = r^2$

Where,

(h, k) is the center of the circle,

r = radius of the circle,

Here, (h, k) = (0, 0)  ( origin ),

r = 7 units,

Hence, the equation of the circle is,

$(x-0)^2 + (y-0)^2 = 7^2$

$\implies x^2 + y^2 = 49$

Answer 2

$\bf \textit{equation of a circle}\\\\ (x-{{ h}})^2+(y-{{ k}})^2={{ r}}^2 \qquad \begin{array}{lllll} center\ (&{{ h}},&{{ k}})\qquad radius=&{{ r}}\\ &0&0&7 \end{array}$