% s=solve('x-xd+(z-zd)*t=0','(x-l 1*cos(theta))^2+y^2+(z+l 1*sin(theta))^2-l2^2=0','(x-xd)^2+(y-yd)^2+(z-zd)^2-l3^2=0','x,y,z')；

Adding% before the second line of this sentence may not help you. It looks tired, but there must be something wrong with this sentence.