 In this video, practice problems too, we're given an equation of a circle and we're asked to find the radius and the coordinates of the center of that circle. And so for the radius, it's helpful to remember that this number represents the radius squared. And so we need to remember that in order to find the radius, all we need to do is find the square root of that number. So our radius in this equation is eight. And then to find the center of the circle, it's helpful to have the equation down here to remind us that the hk represents the xy coordinates of the center. And we're actually going to find the opposite sign of the given signs in the equation. So the center of the circle because that's a positive five becomes negative five and the negative seven becomes a positive seven. It's important to remember that this formula was derived from the distance formula and so we have to find the opposite signs to find the coordinates of that center. Problem. We're again going to find the radius by remembering that the radius is represented by taking the square root of that given number. In this case now, that's not a perfect square, so that's where we're going to have to do some simplifying of radicals. And so we're going to simplify root eighty and the biggest square root that goes into the biggest perfect square that goes into eighty is sixteen. And so to simplify root eighty, that will be four root five as the radius of our circle. And then to find the center again, we're just going to take the opposite signs of the x and y values in the equation. Negative eight becomes positive eight, negative ten becomes positive ten. And so one more practice problem. We're going to start with the radius again and remember the radius is going to be represented by setting that equal, taking the square root of that number. The square root of a hundred of course is ten, our radius of the circle is ten. And then for the center of this circle, you'll notice that I do have an x value in here but nothing with the y. Keep in mind when there's no number there that actually could be rewritten as x plus six squared plus, we could put a y plus zero there and that represents the y coordinate of the center of our circle. So the center value is going to be the opposite of positive six, which is negative six. And then the opposite of zero is just zero. So anytime you don't have a constant number in there with the x or y value, that just means that that coordinate is going to be zero.