- #1

smakhtar

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## Homework Statement

A triangle has verticies A(-2,1,3), B(7,8,-4), and C(5,0,2). Determine the area of the triange ABC.

The correct answer is 35.9 square units.

## Homework Equations

Has to be done by using dot product and/or cross product.

Dot product: a(dot) b= |a||b|cos(theta)

Cross product: a x b= |a||b|sin(theta)

||- this is used to indicate magnitude

## The Attempt at a Solution

AC=(5-(-2),0-1,2-3)

=(7,-1,1)

AB= (7-(-2),8-1,-4-3)

=(9,7,-7)

BC=(5-7,0-8,-1-4)

=(-2,-8,6)

I tried using this formula AB (dot) BC x AC, and I got 358 units squared, which is incorrect. I am trying to get to the correct answer mentioned above. What would be the formula that would give me the correct answer? Please reply as soon as possible