SinX is defined for any angles [0,∞) ??? 1. The problem statement, all variables and given/known data SinX is defined for any angles [0,∞) 2. Relevant equations Ok, the domain of sinX is -∞< x < ∞ 3. The attempt at a solution Someone said "You are confused due to fact that Sin(-x)= - sin(x)." Does it mean that just because sinX is not exactly -sinX, sinX will be undefined for all the negative angles since they will produce negative sine function values and we are only interested in positive sine function? Thanks.