# Thread: Consider the following three points in R^3

1. ## Consider the following three points in R^3

Consider the following three points in R^3:
P(−2, 5, 1), Q(0, 3, 1), R(3, 3, 5)
and let a =P Q(vector),
b =P R (vector),
c =QR (vector)

(a) Calculate the following if possible, or explain why it is not possible to do so:
(i) a × b (ii) c × (a · b) (vi) (b × a) · c (vi) (a · b) · c
(b) Use the cross product to find the area of the triangle with vertices P, Q and R.

2. Originally Posted by singing
Consider the following three points in R^3
:
P(−2, 5, 1), Q(0, 3, 1), R(3, 3, 5)
and let a =P Q(vector),
b =P R (vector),
c =QR (vector)

(a) Calculate the following if possible, or explain why it is not possible to do so:
(i) a × b (ii) c × (a · b) (vi) (b × a) · c (vi) (a · b) · c
(b) Use the cross product to find the area of the triangle with vertices P, Q and R.
PR (vector) = [(Rx - Px), (Ry - Py), (Rz - Pz)] ..... now continue....

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