code for diagram for ladder problem

th is uses arrow commands found in previous diagrams in this worksheet

> pt:=[-9/sqrt(3)*sin(Pi/6),-9/sqrt(3)*cos(Pi/6)];
lines:=plot({[[-20,7], [20,7]], [[-20,0],
[-18/sqrt(3),0]], [[0,0],[20,0]],[[0,0], [-10/sqrt(3.),-10]],[[-10/sqrt(3.)-18/sqrt(3),-10],
[-18/sqrt(3),0]]},thickness=3,color=blue):
m1:=dblabeledarrow([-11,0],[-11,7],[.2,1,1],`7
ft`,[0,-1],16,green):
m2:=dblabeledarrow(pt,[-18/sqrt(3),0],[.2,1,1],`9
ft`,[0,1],16,green):
pt2:=fsolve(sqrt(3)*(x+18/sqrt(3))=x/2,x):
pt3:=sqrt(3.)*(pt2+18/sqrt(3.)):
angletheta:=arctan(.5):
anglealpha:= Pi - 2*Pi/3 - angletheta:
l1:=plot(x/2,x=pt2..14,thickness=3,linestyle=3):
c1:= circarrow([0,0],[9,0], angletheta, 2,`theta`,
[ 7, 0],14,green):
c2:= circarrow([0,0],[-10,-5],anglealpha, 2,`alpha`,
[ 7, 0],14,green):
txt:=plots[textplot]({[ 1,-1,`C`],[14,9,`B`]
,[pt2-2,pt3, `A`]},font=[TIMES,BOLD,18]):
dsk1:=plottools[disk]( [pt2,pt3],.55,color=blue):
dsk2:=plottools[disk]( [14,7],.55,color=blue):
plots[display]({lines,m1,m2,l1,c1,c2,txt,dsk1,dsk2},
scaling=constrained,view=[-20..20,-20..20],axes=none);