What is the smallest interior angle of triangle ABC?

[~Sam~]

Homework Statement

Find the smallest interior angle of the triangle ABC whose vertices are given.
A = (3,1,-2), B = (3,0,-1), C = (5,2,-1)

Homework Equations

I think the equation arccos( U dot V / (lengthU)(lengthV)

The Attempt at a Solution

What i did is tried the formula for all combinatations: AB, BC, AC to get all the angles, and which ever was the smallest I choose. Unfortunately I do not get the correct answer.

 

[Mark44]

Show us what you did. You only need to find the angles between two pairs of line segments. Once you know two of the angles, you can find the third pretty easily.

 

[HallsofIvy]

All most the same thing but instead of using the dot product you could use the "cosine law" to find the angles.