Q1: The points A, B and C have position vectorsa,bandcrespectively, relative to the origin O.

Show that the area of triangle OAB is

(The "a" and"b" above are vectors)

Q2: The points A, B and C have position vectorsa,bandcrespectively, relative to the origin O.

Find the length of projection of AB on AC ifa=i- 5j+ 3k,b= 2j-4kandc=i+j

My answer for Q2 is ...is it correct?

Thank you for helping!