Yooo finally someone that plays
A 40 degree angle: go from the right positive side of the x-axis and go left (left is positive degrees) forty degrees, which is a little less than halfway in quadrant 1.
(x+4)
Hope this helps! If it is wrong, or is lacking clarification, don't hesitate to ask for help!
One way it's useful is in the application of phasors in physics. Phasors require you to add up vectors of two different angles, so the cosine angle addition formula can be used if you already know the cosine and sine of the original vector angles.
(a) 64
divide 16 by .25 and you will get 64
(b) 34
multiply 40 by .85
