Question

find the angle between the vectors a = I^ + 2j^ - k^ and b = -I^ + j^ -2k^

Answer 1

nothing obvious about it so use the dot product:

\(\vec a \bullet \vec b = |\vec a||\vec b| cos \theta\)

Answer 2

can u pls solve it

Answer 3

can't. site has rules about stuff like that.

but i can tell you that, if \(\large \vec a = a_x \hat i + a_y \hat j + a_z \hat k\) and \(\large \vec b = b_x \hat i + b_y \hat j + b_z \hat k\), then \(\large \vec a \bullet \vec b = a_xb_x + a_yb_y + a_zb_z\)