IPython notebook uses MathJax to render LaTeX inside html/markdown. Just put your LaTeX math inside $$.
$$c = \sqrt{a^2 + b^2}$$
Or you can display LaTeX / Math output from Python, as seen towards the end of the notebook tour:
from IPython.display import display, Math, Latex
display(Math(r'F(k) = \int_{-\infty}^{\infty} f(x) e^{2\pi i k} dx'))
