The angle between two planes is the angle between the normal to the two planes. Read this lesson on Three Dimensional Geometry to understand how the angle between two planes is calculated in Vector form and in Cartesian form. The understanding of the angle between the normal to two planes is made simple with a diagram. A solved example, in the end, is also explained to understand how the calculation is performed.
3-D Geometry: The Plane
In Mathematics, ‘planes’ form an important part of 3-D geometry. What is a plane? It is a two-dimensional figure extending infinitely in the three-dimensional space but has no thickness. You can imagine a plane to be an extended number of lines arranged together side by side in the three-dimensional space.
The Angle Between Two Planes
Just like the angle between a straight line and a plane, when we say that the angle between two planes is to be calculated, we actually mean the angle between their respective normals. Thus, we are now actually going to learn how the angle between the normal to two planes is calculated. A close look at the figure below explains this clearly.