Question

p =2i +3j-k q =2i-5j+2k

Answer 1

Vector algebra. ..
P = 2 i +3 j - k
Q = 2 i - 5 j + 2 k

Dot product: 2*2-3*5-1*2 = -13
| P | = sqrt (2^2+3^2+1)= sqrt (14)
|Q | = sqrt(2^2+5^2+2^2)= sqrt(33).
Angle between P and Q = θ.
Cos θ = -13/[ sqrt(14*33)]