8. A pentagon (which can be convex or concave) is formed by several identical equilateral triangles. Find the degree measures of the interior angles of this pentagon.
8. From the problem, we know that the interior angles of the pentagon can be set as $60^{\circ} x_{i}(i=1,2, \cdots, 5)$ and $x_{i} \neq 3$. Then,
$$
x_{1}+x_{2}+\cdots+x_{5}=\frac{3 \times 180^{\circ}}{60^{\circ}}=9 \text {. }
$$

Thus, the equation is transformed into finding the number of positive integer solutions. It is easy to see that the solutions are
$$
(2,2,2,2,1),(4,2,1,1,1),(5,1,1,1,1) \text {. }
$$

Therefore, the interior angles of the pentagon are
$\left(120^{\circ}, 120^{\circ}, 120^{\circ}, 120^{\circ}, 60^{\circ}\right)$ (as shown in Figure 3),
$\left(240^{\circ}, 120^{\circ}, 60^{\circ}, 60^{\circ}, 60^{\circ}\right)$ (as shown in Figure 4),
$\left(300^{\circ}, 60^{\circ}, 60^{\circ}, 60^{\circ}, 60^{\circ}\right)$ (as shown in Figure 5).