User:HannsEwald/sandbox


 * $$K = \frac{RT - S^2}{\left( 1 + P^2 + Q^2 \right)^2}$$


 * $$K = \frac{RT−S^2}{(1+P^2+Q^2)^2}$$

Original from Differential geometry of surfaces
 * $$K = \frac{(RT − S^2)}{\left (1 + P^2 + Q^2\right )^2}$$