Key to MATLAB Exercise 9 SchoolofMathematicalSciencesXiamenUniversityhttp://gdjpkc.xmu.edu.cn 3) > figure(3); surf(X,Y, 2); grid on >> clear close all >> tlinspacet(0,6),x=0.52;y=0.14^3;z=9(c08(2*t) > plot(x,y, z); grid or B点口 > theta=linspace(-pi/2, 0); leq= linspace(-pi, pi) > TTHETA, LEQImeshgrid( theta, leg) >>X=COS(THETA).sin(LEQ): Y=cos(THETA). "cos(LEQ): Z=sin(THETA) >> mesh(X, Y, Z); axis equal Key to Ex9-4Key to MATLAB Exercise 9  School of Mathematical Sciences Xiamen University  http://gdjpkc.xmu.edu.cn  Key to Ex9­4  3) >> figure(3); surf(X,Y,Z); grid on  4.  >> clear; close all;  >> t=linspace(0,6); x=0.5*t.^2; y=0.1*t.^3; z=9*( cos(2*t));  >> plot3(x,y,z); grid on  5.  >> theta=linspace(­pi/2,0); leq=linspace(­pi,pi);  >> [THETA,LEQ]=meshgrid(theta,leq);  >> X=cos(THETA).*sin(LEQ);Y=cos(THETA).*cos(LEQ); Z=sin(THETA);  >> mesh(X,Y,Z); axis equal;