[填空题]
The Great Pyramid of Giza can be mo2vu5tpdbhe : 9d(ks qz( hq+9dwph7cb+/o d+ctelled by a right-pyramid with a square base. A scale model of the Great Pyramid of Giza qk(hsc(97pbzdc++ t /+w hqdois shown below.
The vertices $\mathrm{A}$, $\mathrm{B}$ and $\mathrm{C}$ have coordinates $\mathrm{A}$(1,5.5,0), $\mathrm{B}$(6.5,0,7) and $\mathrm{C}$(12,5.5,0) relative to a fixed origin O near the pyramid. All distances are measured in centimetres.
1. 1. Find $\overrightarrow{\mathrm{AB}}$ .
2. Find $\overrightarrow{\mathrm{AC}}$ .
2. Find $\overrightarrow{\mathrm{AB}} \times \overrightarrow{\mathrm{AC}}$ .
3. Hence, or otherwise, find the surface area of the scale model, not including the base. ≈ $cm^2$
