7. As shown in Figure 2, in plane $\alpha$, $\triangle A B C$ and $\triangle A_{1} B_{1} C_{1}$ are on opposite sides of line $l$, with no common points with $l$, and are symmetric about line $l$. Now, if plane $\alpha$ is folded along line $l$ to form a right dihedral angle, then the six points $A, B, C, A_{1}, B_{1}, C_{1}$ can determine $\qquad$ planes (answer with a number).
7.11.

Notice that after the fold, the three sets of four points
$$
\left(A, B, A_{1}, B_{1}\right) 、\left(B, C, B_{1}, C_{1}\right) 、\left(C, A, C_{1}, A_{1}\right)
$$

are all coplanar, therefore, these six points can determine
$$
C_{6}^{3}-3\left(C_{4}^{3}-1\right)=11 \text { (planes). }
$$