# Why the tetrahedron is equal to the angle of 109.5degrees but it says in an article that if you divide the number of bonds thats the angle but when i divide 4 to 360 the answer is 90 they did not match pls answer my question tnx?

##### 1 Answer

Sep 10, 2017

A tetrahedron is not flat...

#### Explanation:

If you have a flat symmetrical molecule such as Borane

You could model the shape by imagining a carbon atom at

Then the angle between the line joining

#arccos((<1,1,1> . <1,-1,-1>)/(abs(<1,1,1>)*abs(<1,-1,-1>))) = arccos(-1/3) ~~ 109.5^@#