Geometry Problem 721.
Triangle, Orthocenter, Circumcircle, Altitude, Collinear points.

Geometry Problem 722.
Squares, Circumscribed Circles, Collinear points.

Geometry Problem 723.
Squares, Circumscribed Circles, Collinear points.

Geometry Problem 724.
Circumscribed Quadrilateral, Circle, Angle, Incenter, Half the Measure.

Geometry Problem 725.
Kurschak's Dodecagon, Square, Equilateral Triangle, Midpoints, 30, 60 Degrees.

Geometry Problem 726.
Isosceles Triangle, Perpendicular, Midpoint, 90 Degrees.

Geometry Problem 727.
Triangle, Isosceles, Congruence, Angles, Measurement.

Geometry Problem 728.
Triangle, Altitude, Perpendicular, Circumcircle, Midpoint, Intersecting Circles, Concurrency.

Geometry Problem 729.
Triangle, Altitude, Orthocenter, Circumcircle, Perpendicular, Midpoint.

Geometry Problem 730.
Triangle, Altitude, Orthocenter, Perpendicular, Concurrent Lines.