Solution - Properties of circles

The diameter $$\left(d\right)$$ is equal to twice the radius:
$$d=2·r$$

$$d=2\cdot r$$

r=40.311

$$d=2\cdot 40.311$$

$$d=80.623$$

The circumference $$\left(c\right)$$ is equal to two times the radius times π:
$$c=2·r·\pi$$

$$c=2\cdot r\cdot \pi$$

r=40.311

$$c=2\cdot 40.311\cdot \pi$$

$$c=80.623\cdot \pi$$

The area $$\left(a\right)$$ is equal to the radius squared times π:
$$a=r^2·\pi$$

$$a=r^2\cdot \pi$$

r=40.311

$$a={40.311}^2\cdot \pi$$

$$a=1625\cdot \pi$$

The coordinates of the center of a circle are usually, but not always, represented by $$h$$ and $$k$$ in a circle's standard form equation:
$${\left(x-h\right)}^2+{\left(y-k\right)}^2=r^2$$
Identify the $$h$$ and $$k$$ in the equation:
$$a^2+b^2=1625$$
$$h=0$$
$$k=0$$
Center $$\left(0,0\right)$$

To find the $$x$$ -intercept(s), substitute $$0$$ for $$y$$ in the circle's standard form equation
$${\left(x-h\right)}^2+{\left(y-k\right)}^2=r^2$$
and solve the quadratic equation for $$x$$:

$${\left(a+0\right)}^2+{\left(b+0\right)}^2=1625$$

$${\left(a+0\right)}^2+{\left(0+0\right)}^2=1625$$

$${\left(a+0\right)}^2+{\left(-0\right)}^2=1625$$

$${\left(a+0\right)}^2+0=1625$$

$${\left(a+0\right)}^2=1625-0$$

$${\left(a+0\right)}^2=1625$$

$$\sqrt{\left({\left(a+0\right)}^2\right)}=\sqrt{\left(1625\right)}$$

$$a+0=\sqrt{\left(1625\right)}$$

$$a=\pm \sqrt{\left(1625\right)}-0$$

$$a_1=\left(\sqrt{\left(1625\right)}-0,0\right),a_2=\left(-\sqrt{\left(1625\right)}-0,0\right)$$

To find the $$y$$ -intercept(s), substitute $$0$$ for $$x$$ in the circle's standard form equation
$${\left(x-h\right)}^2+{\left(y-k\right)}^2=r^2$$
and solve the quadratic equation for $$y$$:

$${\left(a+0\right)}^2+{\left(b+0\right)}^2=1625$$

$${\left(0+0\right)}^2+{\left(b+0\right)}^2=1625$$

$${\left(-0\right)}^2+{\left(b+0\right)}^2=1625$$

$$0+{\left(b+0\right)}^2=1625$$

$${\left(b+0\right)}^2=1625-0$$

$${\left(b+0\right)}^2=1625$$

$$\sqrt{\left({\left(b+0\right)}^2\right)}=\sqrt{\left(1625\right)}$$

$$b+0=\sqrt{\left(1625\right)}$$

$$b=\pm \sqrt{\left(1625\right)}-0$$

$$b_1=\left(0,\sqrt{\left(1625\right)}-0\right),b_2=\left(0,-\sqrt{\left(1625\right)}-0\right)$$