Question

Use the vector product to find the area of the triangle PQR, P = (5,1,1), Q = (2,−1,3) and R = (−1,4,2).

Answer 1

do you know what the answer is already? i got 1.5, not sure if what im going is right though. Doesnt sound right lol

Answer 2

find vector pq and pr
take the dot product of the two
the cross product will give you the volume

Answer 3

its 12.1 or so.... but im stuck on the easiest bit...

Answer 4

well not the easiest, just getting the vectors pq and pr

Answer 5

find the magnitude of the cross product between PQ and PR. This will give you the area of the parallelogram. Divide this by 2 and you will get the area of the triangle.

Answer 6

you would subtract the coordinates of p from q to get vector pq, same for pr

Answer 7

=1/2((pq.pq)(pr.pr)-(pq.pr)^2)^1/2
=1/2(17x46-14^2^1/2)=12.1

Answer 8

oh ok well the solutions i have are wrong then
for this question;.

Answer 9

partly wrong... .thanks guys/