Sine and cosine question

Question

amtran_bus · Answer

|dw:1360114806926:dw|

amtran_bus · Answer

61.0N at 17 degrees north of east
54N at 8.0 degrees NW

amtran_bus · Answer

Find resultant

amtran_bus · Answer

of each graph

dumbcow · Answer

you add the horizontal and vertical components
horizontal:
$$61 \cos(17) + 54 \cos(98)$$
vertical
$$61 \sin(17) +54 \sin(98)$$
**Note, you have to use the coterminal angles

amtran_bus · Answer

Well, here is where I was stuck. On the first one, I know that sine is used to find the y value.  However, why do you use cosine on the second graph to get the y value?

amtran_bus · Answer

It seems as if because they are in a different quadrant the function used is different.

amtran_bus · Answer

61sin17 gives 17.8, which is the y value
But 38sin64 gives 16.7, which is the X value.  Why?

dumbcow · Answer

sorry i am confused , why are there 2 graphs?
you want the resultant vector from the 2 given vectors on a single graph right?

amtran_bus · Answer

Sorry for the confusion, these graphs came from a single one with ten different vectors on it.  For each one was a different magnitude and angle.  I want the sine and I value (which is X) and the J value (which is Y) for each.  So for each of these graphs.  This is for physics.

amtran_bus · Answer

(The cos, which is the I )

dumbcow · Answer

ok X value is magnitude*cos(angle)
Y value is magnitude*sin(angle)

amtran_bus · Answer

But why does the answer switch between graph one a 2?  

I use one method for graph one but the same method does not work for 2.

dumbcow · Answer

are you sure you are using correct angle

amtran_bus · Answer

61.0N at 17 degrees north of east
54N at 8.0 degrees NW

dumbcow · Answer

example:
8 degrees west of north  = 98 degrees

dumbcow · Answer

or is it 8 degrees north of west = 172 degrees
?

amtran_bus · Answer

RIght, graph one= 61N 17 degrees
Graph 2= 54N 8 degrees|dw:1360116647883:dw|