Question

Two vectors are given by A=3i+4j and B=2j-5j calculate their dot and cross products

Answer 1

Answer:

dot product: A.B = -14

cross product: A×B = -23k

given:

A= 3i+4j and B=2i-5j

dot product:

A.B =(3i)(2i) + (4j)(-5j) (since i.i = 1)

= 6 - 20

= -14

cross product:

A×B = detrminant symbol

i j k

3. 4. 0

2 -5 0

= i(0+0) - j(0+0) + k(-15-8)

= 0+0+k(-23)

= -23k