randRange(-9, 9) randRange(-9, 9) randRange(1, 7) H === 0 ? "x^2" : expr(["^", ["+", "x", -H], 2]) K === 0 ? "y^2" : expr(["^", ["+", "y", -K], 2])

The equation of a circle `C` is `expr(["+", X2T, Y2T]) = R * R`.

What are its center `(h, k)` and its radius `r`?

`(h, k) = (`H`,` K`)`

`r = {}`R

The equation of a circle with center `(h, k)` and radius `r` is `(x - h)^2 + (y - k)^2 = r^2`.

We can rewrite the given equation as `(x - negParens(H))^2 + (y - negParens(K))^2 = R^2`.

Thus, `(h, k) = (H, K)` and `r = R`.