1. Find the direction angles of the vector: 2i-2j-42√k.
2. Find all numbers x for which the angle between c = 3xi + 3j + 3k and d = 3i + 3xj + 3k is π3.
3.Find α given that ?αi+(α-1)j+(α+1)k?=5.
4.Find α given that 5i+6j-2k and αi-24j+8k are parallel.