Ребят,очень срочно)))

[latex] frac{14cos50^circ cdot sin130^circ }{cos10^circ } = frac{14cos50^circ cdot sin(180^circ -50^circ )}{cos10^circ } = frac{7cdot 2cos50^circ cdot sin50^circ }{cos10^circ } =\\= frac{7cdot sin100^circ }{cos10^circ } = frac{7sin(90^circ +10^circ )}{cos10^circ } = frac{7cos10^circ }{cos10^circ } =7[/latex]