用Applet程序中实现绘制三角函数sin(x)当x∈[-π,+π]的曲线图形，其中xi=xi-1+△x,△x=0.05-Applet program used to implement mapping trigonometric sin (x) when x ∈ [-π,+ π] of the curve graph, where xi = xi-1+ △ x, △ x = 0.05