$cos80+\sqrt 3.sin80=A$ olsun
$\frac{1}{2}.cos80+\frac {\sqrt 3}{2}.sin80=\frac{1}{2}A$ olur ve;
$sin30=\frac{1}{2}$
$cos30=\frac {\sqrt 3}{2}$ oldugundan
$sin30.cos80+cos30.sin80=\frac{1}{2}A$ buda
$sinx.cosy+siny.cosx=sin(x+y)$ kuralından
$sin110=\frac{1}{2}A$ ve $A=2.sin110$