A line makes angles `alpha, beta, gamma, delta` with the diagonals of a cube, prove that `cos^2alpha + cos^2beta + cos^2gamma + cos^2 delta = 4/3`

If a line makes anles alpha, beta, gamma with the coordinate axes, porve that sin^2alpha+sin^2beta+sin^2gamma=2

If alpha,beta,gamma are direction - angles of a line prove that cos2 alpha+cos2beta+cos2gamma=-1

State whether it is true or false:If a line makes angles alpha, beta, gamma which positive direction of axes then cos 2alpha+ cos 2beta+cos 2gamma=1 .

If a vector makes angles alpha, beta, gamma with x, y and z axes respectively, then cos alpha, cos beta, cos gamma are known as:

If a line makes an angle alpha, beta, gamma with x axis, y axis and z axis , then : sin^2 alpha+ sin^2 beta+ sin^2 gamma =.......