Question

http://onlineexamhelp.com/wp-content/uploads/2014/08/9709_s14_qp_13.pdf
Q-07

Answer 1

use a dot product

Answer 2

i would start by subtracting A from B and C to move the setup so that A is at the origin

Answer 3

@amistre64 i am not good with vectors, dot product to find the angle between the directions of A and which letter

Answer 4

vectors are just things pointing to other things ... subtraction, addition, mutliplication are the basic math operations that you play with for this

Answer 5

by subtracting A from all the points, we move this thing to the origin at O and as such, the vectors from A to B abd A to C are defined for use

Answer 6

can you type the vectors they give you so i dont have to be flipping back and forth to keep track of information?

Answer 7

\[OA \left(\begin{matrix}1 \\ 2\\ 3 \end{matrix}\right)\]
\[OB \left(\begin{matrix}0 \\ -1\\ 7 \end{matrix}\right)\]
\[OC \left(\begin{matrix}2 \\ 4\\ 7 \end{matrix}\right)\]

Answer 8

now subtract OA from the others

Answer 9

can i ask a question what happens when we subtract OA from OB and OC.

Answer 10

for instance:

B (0, -1, 7)
-A ( 1, 2, 3)
-----------
B' (-1,-3,4)

Answer 11

when we subtract we are moving the triangle to the origin so that the angle at A is at the origin and the vectors from A to B and A to C are defined for the required operations

Answer 12

at the moment, we dont have a triangle defined by vectors, we have the points of a triangle defined by vectors.


we want to know what vectors define the triangle itself so that we can work the problem