Question

What is the length of median AD if AB and AC are resp. represented by I+j and 3i+j-4k?

Answer 1

Answer:

AB+BC=AC

or, BC=AC-AB= (3i+j-4k)-(i+j)=2i-4k

BD=BC/2=i-2k

AB+BD=AD

or,AD= i+j+i-2k=2i+j-2k

Length of AD=√{2²+1²+(-2)²}=3