`bbv = bbi + 2bbj, bbw = 2bbi - bbj` Use the Law of Cosines to find the angle `alpha` between the vectors. (Assume `0^@

You need to use the dot product to find the cosine of the angle between the vectors v and w, such that:

`cos alpha = (v*w)/(|v|*|w|)`

You need to evaluate the product of the vectors v and w, `v = v_x*i + v_y*j, w = w_x*i + w_y*j` , such that:

`v*w = v_x*w_x + v_y*w_y`

`v*w = 1*2 + 2*(-1)`

`v*w = 2- 2`

`v*w = 0`

Since the product of vectors v*w is 0, it is no need to evaluate (|v|*|w|) since `cos alpha = 0` .

`cos alpha = 0 => alpha = pi/2`

Hence, evaluating the angle between the vectors v and w, yields `alpha = pi/2.`