Please look at the picture through the link. The answer that I entered was c1=4/5, c2=3/5, d1=3/5, and d2=4/5. I came up with the conclusion when I drew a right triangle with a hypotenuse of 1 (unit circle) and a leg with 3/5, and another right triangle with a hypotenuse of 1 and a leg with 4/5. I solved for the missing sides (the cosines). My answer isn't correct, so may someone explain what I've done wrong? Thanks!
https://i.stack.imgur.com/Erfzk.png
Review your class transcript. This should give you a hint on how to start. Also look up the definitions and formulas relating to terminal points, and then with those you can find your answer.
Only one little error......
sin x = 3/5
cos x = 4/5
a = (4/5 , 3/5) this is OK
Rememnber that pi/2 < b < pi....so....the cos is negative in ths quadrant
sin x = 4/5
cos x= -3/5
b= (-3/5, 4/5)
c1, c2 ,d1 , d2 = 4/5 , 3/5 , -3/5 , 4/5
Your answer seems correct.....maybe the way you entered it ???