Answer:
2√5
Step-by-step explanation:
The radius is the distance from the center to a point anywhere along the edge of the circle. To find the distance between these two points, use the distance formula.

You could give all of the fractions a common denominator. You could also solve each of them (1/2=0.5) to see their value and order them through the value.
I wouldn't say so, as if you rearrange that equation you get sqr root y = 12 - 4x. Then you square everything to get the value of y so you would end up with 144 - 16x^2.
Therefore, the x value has a power, so it would be a curved line
I think that using the elimination method is the best, because it is the only method that I use when solving these types of equation. For example, for these two equations, you need to multiply one of the equations by a certain number so that you'd be able to find x and y. The elimination method is the method that tells you to do that. It is also the easiest method.
~Hope I helped!~