Regular Tetrahedron Angle Problems: Finding Angles between Planes and Lines

[Michael_Light]

Homework Statement

ABCD is a regular tetrahedron, i.e. its sides are of equal length. E and F are the mid-points of AB and CD respectively. Find the angle between

a) the plane ABEF and the plane CDEF
b) the plane ABEF and the line AC
c)the line AC and the line EF

Homework Equations

The Attempt at a Solution

For (a), does plane ABEF same as plane ABF while plane CDEF same as CDE?

Can anyone give me some hints? Thank you.

 

[LCKurtz]

Homework Statement

ABCD is a regular tetrahedron, i.e. its sides are of equal length. E and F are the mid-points of AB and CD respectively. Find the angle between

a) the plane ABEF and the plane CDEF
b) the plane ABEF and the line AC
c)the line AC and the line EF

Homework Equations

The Attempt at a Solution

For (a), does plane ABEF same as plane ABF while plane CDEF same as CDE?

Yes to both of those questions. I would work this problem by finding the coordinates of the three points you have used for each plane, calculating the normals to the planes and finding the angle between the normals.