Find the angle between vectors and show formula used u 2i

Find the angle between vectors and show formula used.

u = 2i - 3j

v = i - 2j

u = 2i - 3j

v = i - 2j

IuI = sqrt(13)

IvI = sqrt(5)

u.v = (2i - 3j).(i - 2j) = 2 + 6 = 8

Now u.v = IuI*IvI*cos(theta)

8 = sqrt(13)*sqrt(5)*cos(theta)

cos(theta) = 0.992

theta = 7.125 degree