[tex]e)\\\\h=\frac{a\sqrt{3}}{2}\ \ |*2\\\\a\sqrt{3}=2h\ \ |:\sqrt{3}\\\\a=\frac{2h}{\sqrt{3}}*\frac{\sqrt{3}}{\sqrt{3}}=\frac{2\sqrt{3}h}{3}[/tex]
[tex]f)\\\\ P=\frac{r*(a+b+c)}{2}\ \ |*2\\\\r*(a+b+c)=2P\\\\ra+rb+rc=2P\\\\ra=2P-rb-rc\\\\ra=2P-r(b+c)\ \ \ |:r\\\\a=\frac{2P-r(b+c)}{r}[/tex]
