Thread: Area of a triangle formed by P, Q, and R

hello everyone.

First off, I'd like to say that this is a wonderful site, and I appreciate the help.

Now, onto the question.

I have a plane formed by P(2,0,-3) Q(3,1,0) and R(5,2,2)

I first had to find a vector orthogonal to the plane. I did that by forming 2 vectors using PQ and PR, then getting the cross product.

Now it is asking that I find the area of the triangle that is formed by P, Q, and R. I know there is a formula that I am missing, and it is not in the text book that I can find. I missed that day in class, and now I'm feeling the consequences.

Thank you guys.

The area of the triangle PQR is one-half ||<PQ>x<PR>||.

thank you