Vector A has magnitude 8 & angle 130.B has components Bx= -7.72 & By= -9.2.What is the dot product of 5A & B?

Question

Vectors A & B lie in an xy plane.

b) What is the cross product of 4A and 3B?

Answer 1

Here's the Dot:

A: vector:va

8*Cos(130) =-5.1423 i

8* Sin(130) =6.128356 j

va=-5.1423i+6.128356j

vb=-7.72i+-9.2j

Let:

ai = 5 * (-5.1423)

aj = 5 * (6.128356)

bi = (-7.72)

bj = (-9.2)

5*va dot vb=

(ai * bi) + (aj * bj) =

-83.411596 scalar  "answer"

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here's the 2D cross:

What is the cross product of 4A and 3B

4Ax3B

Let:

ai = 4 * (-5.1423)

aj = 4 * (6.128356)

bi = 3 * (-7.72)

bj = 3 * (-9.2)

Cross product =

(ai * bj) - (aj * bi) ,k

=1135.441 k "answer"

k indicates the resultant points along the

plane's z axis.

Answer 2

Ax is going to be 8*cos(130) ~=:-2.132

Ay is 8*sin(130) ~= 7.711

5A is going to be just 40*cos(130) etc.

So I get that 5A<dot>B~=436.993

Can you do the arithmetic from there?

I get that 4Ax3B=-(235.399, -714.311)