Question

The figure below shows a cuboid labelled ABCDEFGU Point O is the mid point of BD. AB 15 cm, BC =8 cm and CF=5 cm.

Calculate the angle between the lines OF and OF

Answer 1

∢EOF=
EO = OF = √5² + 8.5²
= 9.8615
 ^a2 = b² + c² − 2bc Cos A
15² = 9.8615² + 9.8615² − 2 x 9.8615² cos A
cos A = −0.156822
A = 99.02