A B C triangle
a = projection(A, line(B, C))
b = projection(B, line(A, C))
c = projection(C, line(A, B))
draw(A, B, C)
draw(a) ; draw(b) ; draw(c)
draw(segment(A, a), dotted)
draw(segment(B, b), dotted)
draw(segment(C, c), dotted)
draw(barycenter(A, B))
draw(barycenter(B, C))
draw(barycenter(C, A))
draw(circle(a, b, c))