Now |A|= 2 × 1 – 2 × 5

|A|= 2 – 10

|A|= –8

Now |B|= 4 × 5 – 2 × (–3)

|B|= 20 + 6

|B|= 26

⇒ |A|×|B|= –8 × 26

|A|×|B|= –208

Now

|AB| = 18 × (–1) – 19 × 10

|AB| = –18 – 190

|AB| = –208

Hence |AB| =|A|×|B|.