After you have explored the 'Orthogonal Circles' environment, try this challenge. The black dots fix the vertices of an isosceles triangle The red, green and blue dots fix the radii of the circles Is it possible to make the three circles pairwise orthogonal, i.e. red orthogonal to green, green orthogonal to blue and blue orthogonal to red? Can this be done for any isosceles triangle? Can you prove or disprove this?