Question

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

Answer 1

`\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}`

Answer 2

`x^2 + y^2 = 49`

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`