Can you help me please, please answer seriously, no links please​

Centre:

Radius =

Step-by-step explanation:

General formula for a circle: , where the radius of the circle and is the centre of the circle.

To find the centre and radius of the circle we should re-write the given equation in the form of the general formula.

So, put the terms with the same variables together:

We can see that there is a common factor of , so let's simplify by dividing by :

Here we can get it into the general formula by completing the square.

We do this by turning a quadratic with form into the form , where d is half of the coefficient of , e is and c is the constant of the quadratic.

So let's re-write the equation of the circle:

Simplify:

Now we can see that it's very similar to the general equation and all we have to do is bring the over to the right side.

So, now we can find the radius and centre.

answer is  

a.

7 in. x 11 in.

hope you get this right.