\\\alpha=48^\circ20'\implies \frac{\alpha}{2}=24^\circ10'\\24^\circ10'+90^\circ+\frac{\beta}{2}=180^\circ\implies \frac{\beta}{2}=65^\circ50'\\P_{romba}=a\cdot v\quad (*1)\\\sin\frac{\alpha}{2}=\frac{\frac{e}{2}}{a}=\frac{e}{2a}\quad (*2)\\\sin\alpha=\frac{v}{a}\implies v=a\cdot\sin\alpha\quad (*3)\\