Consider points A, B, C and D such that ∠ACB = 30◦, ∠CBD = 26◦, ∠DBA = 51◦ and ∠DAC = 13◦. Compute all possible values of the ∠BDC.
This is a 3D-Geometry problem. So I am assuming ABCD is a tetrahedron. It is not specified which is the base of the tetrahedron.