The resultant in the x-direction:
Rx = F1 + F2 = 2.5 N - 1 N = 1.5 N .
The resultant in the y-direction:
Ry = F3 + F4 = 2 N - 3 N = -1 N.
Answer:
If the ray of light is deflected by 45 degrees by the first mirror its total deflection by mirror (I) is 90 deg. (incident = 45 and exit ray equals 45 deg)
The second mirror will cause a net deflection of 90 degrees and the total deflection will be 180 deg or in opposite direction to the incident ray.
To get x on its own, you times the 3 over to the other side so the 3 cancels out on the LHS.
~ x greater than or equal to -18
(C)
A > Is the correct answer :)