Вычислите $$frac{sin^2765^circ}{1-cos420^circ}$$

$$frac{sin^2765^circ}{1-cos420^circ}$$$$=frac{sin^245^circ}{1-cos60^circ}=frac{left(frac{sqrt2}2right)^2}{1-frac12}=frac{frac24}{frac12}=1$$