Question

Question posted below attachment :

Answer 1

In the question solved above, how do I know that I have to take z=+1/2 & not -1/2

Answer 2

Because the angle would no longer be (pi/3) if cos(theta)=-1/2
Please help!!

Answer 3

@Mashy this one is genuine!

Answer 4

@thomaster help instead of chat maybe :3 ?

Answer 5

@sayakdbz I would help you, if I knew math...

Answer 6

LMAO @thomaster a'ight :P

Answer 7

ANYONE ?

Answer 8

if cos (theta) = -1/2
then theta = 120 degrees ya?

now read the first line of the question again, there lies your reason why theta cannot be 120 degrees and hence you cannot take -1/2

Answer 9

yeah. I got it later :)