The document finds the angle between two vectors representing the face diagonal and body diagonal of a rectangular block. The vectors are defined as A=ai+aj and B=ai+aj+ak. The angle between the vectors is calculated to be 53.3 degrees, or approximately 70 radians. The document also finds the value(s) of q that make another two vectors, 3=q+q2 and B=i+j+k, perpendicular. Setting their dot product equal to 0 and solving yields that q=0 or q=1 are the values where the vectors are perpendicular.