Thread: vector angle

two forces N and N are given by





a) calculate, correct to the nearest degree, the angle between the directions of and


so using the dot product formula

I end up with



I think i have done this right however the angle i inverse cos is negative, so do I draw up a cast diagram to find the angle? if so is it the angle 180 - 72.98?

I think that you made a mistake in the dot product. I get .

Recall that if the dot product is negative the angle is obtuse.

yes i mis-calculated. i now get the angle 75.7.

so I'm thinking I do 180-75.7 = 104.3 ?