1. By Abdul Chebly

2.  obtuse angle- an angle that’s less then 180 and higher then 90 degrees.  Right angle- an angle that is 90 degrees.

3.  acute angle- an angle less then 90 and higher then 0 degrees.  Adjacent angle - Either of two angles having a common side and a common vertex.

4.  Vertical angle- one of two opposite and equal angles formed by the intersection of two lines.

5.  Scalene triangle- a triangle with no two sides of equal length Isosceles triangle- a triangle with two equal sides

6.  Equilateral triangle- a three-sided regular polygon.

7. Parallel lines- lines extending in the same direction.  Perpendicular lines- lines that cross each other.

8.  Transversal- a line intersecting two or more lines.

9.  Circle- a closed plane curve consisting of all points at a given distance from a point within it called the center.  Semi-circle- the arc from one end of a diameter to the other

10.  Parallelogram- a quadrilateral having both pairs of opposite sides parallel to each other.  Rectangle- a parallelogram having four right angles.

11.  Square- a polygon having all four sides of equal length.  Pentagon- a polygon having five angles and five sides.

12.  Octagon- a polygon having eight angles and eight sides.  Rhombus- an equilateral parallelogram