An Isosceles Triangle

box -1, -1, 7, 3

A B C isosceles
H = projection(C, line(A, B))

draw
 (A.B.C)
  C.H dashed
  H
end

label
  B, H, C right
  B, A, C double
  C, B, A double
  A.H
  B.H
  A.C double
  C.B double
end