[justify][i]It is given [/i][i]an arbelos (worksheet "Archimedean circle in Arbelos"). Use the button "Play" to explore the construction of radius [math]r_{\left(B\right)}[/math][/i]  [i]of the Archimedean circle in arbelos. Build another Archimedean circle with radius [math]r_{\left(A\right)}[/math][/i][i].  Prove that [math]r_{\left(A\right)}=r_{\left(B\right)}[/math][/i] [i]by using the logic GeoGebra functions (van Lamoen, 2014, p. 253). [/i][/justify]

[i]If there are given an arbelos and one of the two Archimedean circles, construct the second Archimedean circle, and prove their equality [/i][size=100][size=150][i][font=Arial] [/font][/i][/size][/size][i][font=Arial][/font]by using the button "Relation".[/i]