Define :
Direction cosines of a straight line,

Define : Direction angles of a straight line,

Define : Direction ratios of a straight line.

Find the direction cosines of a straight line which is situate on yz-plane and inclined at an angle 60^@ with poistive direction of z-axis.

If the directions cosines of a straight line are ltk,k,kgt then

Can the numbers 1, 2, 3 be the direction cosines of a straight line?

Prove that 1,1,1 cannot be direction cosines of a straight line.

Prove that 1,1,1 cannot be direction cosines of a straight line.

Prove that 1,1,1 cannot be direction cosines of a straight line.

A straight line in the xy-plane makes an angle pi/4 with y-axis. Find the direction cosines of the straight line.

Find the direction cosines of the straight line joining the points : (4, 3, -5) and (-2, 1, -8)