D Question 18 100 pts You are given an angle measured counte

D Question 18 100 pts You are given an angle measured counter-clockwise from the positive x axis to a unit vector u 1\' u Determine the components u1 and e ST 2 3 1 2 2 Screenshot saved The screenshot was added to y One Drive OneDrive

Solution

theta = 5pi/3

cos(5pi/3) first :
5pi/3 is in quadrant 4
So, refangle = 2pi - 5pi/3
refangle = pi/3

We know cospi/3 = 1/2

And we know from CAST rule that cos is positive in fourth quad
So, cos(5pi/3) = 1/2 also

sin(5pi/3) :
refangle = pi/3
sin(pi/3) = sqrt(3)/2

But sin is neg in quad 4

So, sin(5pi/3) = -sqrt(3)/2

So, answer :

(1/2 , -sqrt3/2)

option E