Angle between two lines in space |
Angle between two planes in space |
Angle between a line and a plane |
The angle t between two lines is the angle between two direction vectors of the lines.
Take line a with direction vector u and line b with direction vector v.
That is:
u.v= ||u||.||v||.cos(t)
and then:

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The angle between two planes is given by the angle between the normal vectors,
n1 and n2, that is:
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Let's name t to the angle which line makes with plane, v the direction vector of line and n the normal vector of the plane.
Then:

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