8-1建立一个图形窗口，使之背景颜色为红色，并在窗口上保留原有的菜单项，而且在按下鼠标左键之后显示出LeftButtonPressed字样。本体程序：clc;hf=figure('color','r','windowbuttondownfcn','axisoff;text(0.1,0.5,''LeftButtonPressed'',''fontsize'',30)')运行结果：hf=18-3利用图形对象绘制下列曲线，要求先利用默认属性绘制曲线，然后通过图形句柄操作来改变曲线的颜色、线型和线宽，并利用文字对象给曲线添加文字标注。（1）clc;x=0:5*pi;y=exp(-0.2*x).*cos(x)+2;h=plot(x,y);set(h,'Color',[1,0,0],'LineStyle',':','LineWidth',2);（2）程序：t=0:2:100;x=t.*t;y=5*t.^3;hf=plot(x,y);set(hf,'color','b','linestyle',':','marker','p','linewidth',0.3);8-4利用图形对象绘制下列三维图形，要求与上题相同。（1）程序：t=0:0.1:2*pi;x=cos(t);y=sin(t);z=t;hf=plot3(x,y,z);运行结果：8-5以任意位置子图形式绘制出正弦、余弦、正切和余切函数曲线。clc;x=-2*pi:0.01:2*pi;y1=sin(x);y2=cos(x);axes('Position',[0.1,0.6,0.2,0.2])plot(x,y1);ht=get(gca,'Title');set(ht,'Color','r');title('y=sin(x)')hc=get(gca,'Children'),set(hc,'Color','b','LineWidth',1.5)axes('Position',[0.6,0.6,0.2,0.2])plot(x,y2,'r');ht=get(gca,'Title');set(ht,'Color','r');title('y=cos(x)')axes('Position',[0.1,0.1,0.2,0.2])fplot('tan(x)',[-1.5,1.5]);ht=get(gca,'Title');set(ht,'Color','r');title('y=tan(x)')axes('Position',[0.6,0.1,0.2,0.2])fplot('cot(x)',[0,1,3]);ht=get(gca,'Title');set(ht,'Color','r');title('y=cot(x)')