Angles Acute Angle Definition: An Acute angle is smaller than 90 degrees but bigger than 90 degrees. Obtuse Angle Obtuse angle is a angle between 90-180 degrees. Straight Angle A Straight angle is an angle between 180 degrees. Right angle A Right angle is an angle of 90 degrees. Quadrilateral A Quadrilateral is a 4 sided object. Square A square is a shape with 4 equal sides and 4 right angles. Rectangle A shape with 4 sides and 4 right angles. Rhombus A parallelogram with equal acute angles. Trapezoid A four-sided shape with one pair of parallel sides. Parallelogram A plain four-sided rectangular figure. We got our information from: http://www.google.com http://www.mathisfun.com/