Forum de Mathématiques: Maths-Forum

Let ABCDEFGH a cube be, as shown on the picture. Let's denote AB=a. I,J and K are the middles of [AB],[BC]and[BF]. 1. Justify that IJK is an equilateral triangle. 2. Calculate IK. 3. What is the area of the triangle BIK ? 4. Calculate the volume of the tetrahedron BIJK. 5. Calculate the length of th...