Geometry Shapes and angles By: Alyssa & Leah Some fun geometry games and more. We picked out some really fun geometry games. http://www.coolmath-games.com/0-poolgeometry/ http://www.mathplayground.com/alienangles.html http://www.xpmath.com Here are some definitions. Acute Angle- 89 degrees-1 degree Obtuse Angle-179 degrees-91 degrees Straight Angle-180 degrees Right Angle-90 degrees Rhombus-A quadrilateral with a set of parallel lines. A quadrilateral with 2 short sides and all parrallel lines. A quadrilateral with all parallel lines that have equal lines on opposite sides. A quadrilateral with equal opposite sides with one set of perpendicular lines. Square-A quadrilateral with all equal sides and angles.