2. The base $\triangle A B C$ of the tetrahedron $P-A B C$ is an equilateral triangle with side length 3, $P A=3, P B=4, P C=5$. Then the volume of the tetrahedron $P-A B C$ is ( )
A: 3
B: $\sqrt{10}$
C: $\sqrt{11}$
D: $2 \sqrt{3}$
Answer C.
Analysis $V_{P-A B C}=V_{A-P B C}=\frac{1}{3} \times\left(\frac{1}{2} \times 3 \times 4\right) \times \sqrt{3^{2}-\left(\frac{5}{2}\right)^{2}}=\sqrt{11}$.