THEOREM OF THE DAY: Lambert’s Formula

If $T$ is a triangle in the hyperbolic plane of (negative) Gaussian curvature $K$, with angles $\alpha ,\beta$ and $\gamma$, then the area of $T$ is given by 

Area of $T={\displaystyle \frac{1}{K}}(\alpha +\beta +\gamma -{\displaystyle \frac{\tau }{2}})$

where $\tau =2\pi$.

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