Are these nonlinear constraints? I know this a easy question for you, I just a bit forgot the theory and being a bit not confide

Question

0.5 sin⁡〖x_1 〗-0.1≤0 and what about this one :

-l1*sin (x1) -l2*sin (x1+x2) -0.1≤0

Answer 1

All of them are non linear because the sin function is not linear.