4-5.html

(commands for creating the figure above)

> p1:=plot({-sqrt(1-x^2),sqrt(1-x^2)},x=-1..1,thickness=2):
p2:=disk([0,0],1,color=cyan):
p3:=textplot([.8,.9,"y=sqrt(1-x^2)"],color=black,font=[TIMES,ROMAN,14],align=RIGHT):
p4:=textplot([.8,-.9,"y=-sqrt(1-x^2)"],color=black,font=[TIMES,ROMAN,14],align=RIGHT):
display(p1,p2,p3,p4,scaling=constrained);

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