Question

Select the equation of a circle with a center at the origin and a radius 7.

Answer 1

The Solution.

The circle with a center at the origin implies that (a,b) = (0,0).

The equation of a circle is given by;

`\begin{gathered} (x-a)^2+(y-b)^2=r^2 \\ \text{Where a=0, b=0 and r=7 units.} \end{gathered}`

Substituting the values above into the formula, we get

`\begin{gathered} (x-0)^2+(y-0)^2=7^2 \\ x^2+y^2=49 \end{gathered}`

Step 3:

Presentation of the Answer.

Thus, the correct answer is option C / third option.

`x^2+y^2=49`