The acute angle between the curves $x^2+y^2=x+y$ and $x^2+y^2=2 y$ is

A' value of $C$ according to the Lagrange's mean value theorem for $f(x)=(x-1)(x-2)(x-3)$ in $[0,4]$ is

If $T=2 \pi \sqrt{\frac{L}{g}}, \mathrm{~g}$ is a constant and the relative error in $T$ is $k$ times to the percentage error in $l$, then $\frac{1}{K}=$

The angle between the curves $y^2=2 x$ and $x^2+y^2=8$ is