Question

Suppose the magnitude of C=6 and the magnitude of D=4, and l C x D l= 12. Find C dot D?

Answer 1

are these vectors or just regular numbers?

Answer 2

yes

Answer 3

the answer is 12 root 3, but I'm really not sure how to start the problem

Answer 4

it's been some time since I've done vectors lol
give me a minute

Answer 5

what is l C x D l exactly?

Answer 6

cross product?

Answer 7

magnitude of the cross product of C and D?

Answer 8

alright, busting out my old notes for this lol
you know that |C x D| = |C||D|sin(theta) right?

Answer 9

yes

Answer 10

you know all the values there except for theta so you can solve for that

Answer 11

is C dot D= lCllDl cos(theta) also?

Answer 12

yes, so all you need is the angle

Answer 13

how do I find the angle?

Answer 14

|C x D| = |C||D|sin(theta)
(12) = (6)(4)sin(theta)
(12) = (24)sin(theta)
12/24 = sin(theta)
1/2 = sin(theta)

Answer 15

so I plugged in the numbers and got 60 degrees

Answer 16

oh! I got it!

Answer 17

6*4sin(60)= 12 rt 3. phew

Answer 18

thank you!!

Answer 19

yeah no problem, good job!