SOLUTION: A vector is described. Express the vector in terms of i and j. If exact values are not possible, round components to the nearest tenth. A plane with an airspeed of 450 mph is f

Algebra ->  Trigonometry-basics -> SOLUTION: A vector is described. Express the vector in terms of i and j. If exact values are not possible, round components to the nearest tenth. A plane with an airspeed of 450 mph is f      Log On


   



Question 327541: A vector is described. Express the vector in terms of i and j. If exact values are not possible, round components to the nearest tenth.
A plane with an airspeed of 450 mph is flying in the direction N35W.
I have gotten an answer but am not sure if I have done it right. I need some help on this to make sure. Are you to use bearings?

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
A vector is described. Express the vector in terms of i and j. If exact values are not possible, round components to the nearest tenth.
A plane with an airspeed of 450 mph is flying in the direction N35W.
I have gotten an answer but am not sure if I have done it right. I need some help on this to make sure. Are you to use bearings?
North is the positive y-axis
South is the negative y-axis
East is the positive x-axis
West is the negative x-axis

This is the vector.  Its direction is determined by starting from 
north, the positive y-axis, and swinging a vector toward the west,
which is counter-clockwise, by 35°. 



To express this vector in terms of horizontal and vertical
component vectors, we draw horizontal and vertical lines from the
tip of that vector to the x and y axes:



Then these two green vectors are the x-component
and y-component of the red vector:



The actual angle is this vector measured from the 
postive x axis, indicated by this blue arc, which is
90°+35° or 125°



The magnitude of the green horizontal vector is 450cos%28%22125%B0%22%29

Therefore it is the vector 450cos%28%22125%B0%22%29i

The magnitude of the green vertical vector is 450sin%28%22125%B0%22%29

Therefore it is the vector 450sin%28%22125%B0%22%29j

So to write the red vector in terms of the horizontal unit vector
 i and the vertival unit vector j, we have

450cos%28%22125%B0%22%29i + 450sin%28%22125%B0%22%29j

There is no way to get the exact values, so we punch those into a 
calculator and get:

-258.1093964i + 368.6184199j

Or rounded to tenths:

-258.1i + 368.6j

Edwin