Python Pyplot Text with Square Root

I'm trying to annotate my pyplot with the following:

I am able to get the square root of a number, and I am able to get the h-squared, but when I put them together I get a

ValueError: cannot switch from automatic field numbering to manual field specification

Any idea what I'm doing wrong?

import matplotlib.pyplot as plt
x = [1, 2, 3]
y = np.array([[1, 2], [3, 4], [5, 6]])
plt.plot(x, y)
t=97.35713828629935
plt.text(1,5,r'{:3.1f}% greater than $$\sqrt{0.5*$h^2$}$$'.format(t))