# 3D angles- can they exist?

i would like to know if the 'angle' between lets say the walls of a room (ie. the intersection of 3 planes all perpendicular to each other) can be represented in mathematical terms, but as a kind of 3D angle- that is to say not as a combination of 2D angles but as an altogether new form of representing the gap between intersecting planes.
Is there any way to do this and if not why can't these 'angles' be represented in 3D?

Simon Bridge
Homework Helper
Welcome to PF;
Look up "solid angle".

Cool, Simon.

I'm in Linear Algebra right now, so correct me if I'm wrong... But isn't this also what we are talking about with certain linear transformations, which can be rotations in any number of dimensions?

-Dave K

HallsofIvy
Homework Helper
No, a "solid angle" is NOT a rotation in three dimensions, any more than a regular angle is a rotation in two dimensions. You can use an angle, in two dimensions to define a rotation but you will also need to specify a point to rotate about. You can use a solid angle to define a rotation but in three dimensions, you will need to specify a point to rotate about and an axis of rotation.

Simon Bridge