[填空题]
The Great Pyramid of Giza 3*y onb8,utw bcan be mozzh95.sec0wp(xc w .cm4mo 0r delled by a right-pyramid with a square base. A scale mode9zx we45cz.p ro.m cmc 0h0(wsl of the Great Pyramid of Giza is 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. ≈ $cm^2$
