Problem 481.
Triangle, Altitude, Cevian, Perpendicular, Angle.

Problem 482.
Triangle, Circumcircle, Incenter, Excenter, Midpoint, Cyclic Points.

Problem 483.
Square, Angle, 90 degrees, Measurement.

Problem 484.
Square, Angle, 90 degrees, Triangle, Measurement, Proportion.

Problem 485.
Square, Side, Circles, Tangent, Radius, Measurement.

Problem 486.
Tangent circles, Chord, Arc, Midpoint, Collinearity, Congruence.

Problem 487.
Intersecting Circles, Area, Diameter, Parallel, 90 Degrees.

Problem 488.
Triangle, Cevian, Concurrency, Circle, Circumcircle.

Problem 489.
Parallelogram, Triangle, Quadrilateral, Area.

Problem 490.
Tangent Circles, Arc, Radius, Circular Sector, Area.