Area of a triangle using vectors

[Calpalned]

## 1. Homework Statement
Let P = (1,1,1), Q = (0, 3, 1) and R = (0, 1, 4). Find the area of triangle PQR

Homework Equations

## \frac {|PQ × PR|}{2} ## = area (The crossproduct divided by two)

The Attempt at a Solution

I lost my answer key, so I want to check if my final answer of ## \frac {\sqrt {13}}{2} ## is right. Thanks everyone. If it isn't, I'll put up my work. ##

 

[PhysyCola]

Hey there Calpalned. I have worked the problem through, and I am not sure that your answer is correct. Are you sure you have evaluated the cross product correctly?

 

[Calpalned]

Hey there Calpalned. I have worked the problem through, and I am not sure that your answer is correct. Are you sure you have evaluated the cross product correctly?

I took the cross product of ## <-1, 2, 0> ## and ## <-1, 0,3> ## and I got ## (0-0)-(-3-0)+(0--2) ## = ## <0, 3, 2> ## Taking the magnitude, I get the answer in my first post.

 

[SammyS]

I took the cross product of ## <-1, 2, 0> ## and ## <-1, 0,3> ## and I got ## (0-0)-(-3-0)+(0--2) ## = ## <0, 3, 2> ## Taking the magnitude, I get the answer in my first post.

Not correct.

This should have vector components: ## (0-0)-(-3-0)+(0--2) ## . What you have is a scalar.

The x-component of the result, ##\ <0,\, 3,\, 2>\ ## is incorrect.