Thread: cal the angle between the lines

x-3=2-y,z=1, and x=-3,y+2=z-5

My answer is 2pie/3, but the answer should be pie/3. Can any one please tell me where i did wrong, thanx.

Originally Posted by Jojo123

x-3=2-y,z=1, and x=-3,y+2=z-5

My answer is 2pie/3, but the answer should be pie/3. Can any one please tell me where i did wrong, thanx.

Both answers are correct. There are generally two angles between two lines .... an acute angle and an obtuse angle.

You used the dot product and got the obtuse angle. Did the question ask for the acute angle ....?