Question

Calculate the dot product of D and E, where D=7i - 3j + 2k and E=4i + 5j - 3k.​

please show working

Answer 1

Since i dot i = 1 and j dot j = 1 and k dot k = 1 and the other terms are zero

(7 i - 3 j + 2 k) dot (4 i + 5 j - 3 k) = 28 - 15 -6 = 7