You may have been looking at the graph of $\displaystyle{y}={\sin{{x}}}\usepackage{cmbright}\Huge\$ instead of $\displaystyle{y}={\sin{{3}}}{x}\usepackage{cmbright}\Huge\$ . Look at one cycle of the graph of $\displaystyle{y}={\sin{{3}}}{x}\usepackage{cmbright}\Huge\$ just to the right of the y-axis. The function equals 0 when the graph crosses the x-axis. Find the first point to the right of the y-axis where this happens.