(708,#21) A)Find the vector orthogonal to the plane through the points

(708,#21) a) Find the vector orthogonal to the plane through the points P(1,0,0), Q(0,2,0) , R(0,0,3).
b)Find the area of the triangle PQR.
Solution:

a) Let a and b be the vectors defined below. Then the orthogonal vector is the cross product a x b.

Therefore, the vector orthogonal to the plane is
B) We have
= area of parallelogram formed by vectors a and b.
= area of the triangle formed by vectors a, b and a + b

Therefore, the area of the triangle is 7/2.

by:sh