**c21** |
Points
whose reflections on the altitudes form a triangle perspective with ABC |

**c22** |
Points being
the ninecenter of their pedal triangle |

**c23** |
Points being
the orthocenter of their cevian triangle |

**c24** |
Deltoids inscribed
in a triangle ABC |

**c25** |
Inscribed square
with a side on BC |

**c26** |
Triangle given
the vertex A, the circumcenter O and the symmedian point K |

**c27** |
Triangle given
the circumcenter O, the foot Ha of the A-altitude and the foot Wa of the
A-bisector |

**c28** |
Triangle given
the vertex A, the incenter I and the centroid G |

**c29** |
Triangles with
given circumcircle c and with a given point N in c as ninecenter |

**c30** |
Triangle given
the centroid G, the line r containing BC, a point N in AC and a point L
in AB |

**c31** |
Point P with
Simson line parallel to a given line r |

**c32** |
Point P with
given Steiner line r |

**c33** |
Triangle given
the A-median m, the A-bisector d, and the product bc of the sides |

**c34** |
Circle through
A tangent to BC and cutting equal segments in AB and AC |

**c35** |
Given two circles
through A, tangents to BC at B and C, construct a third circle tangent
to the former and to BC |

**c36** |
Triangle with
a symmedian orthogonal to the Euler line |

**c37** |
Triangle given
the incenter I, the centroid G and the orthocenter H |

**c38** |
Triangle given
the angle A, the A-bisector d, and the sum b+c of the sides |

**c39** |
Points of the
circumcircle with Simson line through a given point P |

**c40** |
Lines with
a given orthopole P |