[填空题]
A land surveyor is measuring the .zj,q)pe ys2au0ze nd2c f95uar 7rfnedi9d n3*w 5ys7dea of a triangular plot of land on a smooth hill. She uses a theodolite to determine the coordinates of the corners of the land and finds them to be (-8,20,10),(16,8,7) and (-20,-8,3) , where dne9 d* yisf7 5nd7rw3the coordinates are in metres from a fixed origin where she stands.
Using vectors, determine the area of the land. $m^2$
