front 1 point  back 1 an exact location in space 
front 2 acute angle  back 2 an angle that is less than 90 degrees and smaller than a right angle 
front 3 Hexagon  back 3 a polygon with 6 sides and 6 vertices 
front 4 intersecting lines  back 4 the 2 line segments cross each other at a point 
front 5 parallel lines  back 5 lines that are equal distance apart at every point and they never intersect

front 6 symmetric
 back 6 a figure is symmetric if it can be folded into 2 congruent halves that fit on top of each other. The line of symmetry divides the valentine heart into 2 congruent shapes. 
front 7 line  back 7 a straight path of points that goes on forever in both directions 
front 8 plane  back 8 an endless flat surface 
front 9 perpendicular lines  back 9 2 lines that intersect at a right angle 
front 10 line segment  back 10 part of a line that has 2 end points 
front 11 ray  back 11 part of a line that has 1 end point and extends forever in one direction 
front 12 angle  back 12 a figure formed by 2 rays that have the same endpoint 
front 13 right angle  back 13 an angle that measures exactly 90º 
front 14 obtuse angle  back 14 and angle that measures more than 90º 
front 15 straight angle  back 15 an angle that measures exactly 180º 
front 16 polygon  back 16 a closed shape made up of line segments 
front 17 side  back 17 each of the line segments of a polygon 
front 18 vertex, vertices  back 18 the point where 2 rays meet to form an angle. the points where the sides of a polygon meet. 
front 19 triangle  back 19 a polygon with 3 sides and 3 angles 
front 20 quadrilateral  back 20 a polygon with 4 sides and 4 angles 
front 21 pentagon  back 21 a polygon with 5 sides and 5 angles 
front 22 octagon  back 22 a polygon with 8 sides and 8 angles 
front 23 parallelogram  back 23 a quadrilateral in which the opposite sides are parallel 
front 24 rectangle  back 24 a parallelogram with 4 right angles 
front 25 square  back 25 a parallelogram with 4 right angles and all sides the same length 
front 26 rhombus  back 26 a parallelogram with all sides the same length 
front 27 trapezoid  back 27 a quadrilateral with only 1 pair of opposite sides that are parallel 
front 28 equilateral triangle  back 28 a triangle with 3 equal sides 
front 29 isosceles triangle  back 29 a triangle that has 2 equal sides 
front 30 scalene triangle  back 30 a triangle that has no sides that as the same length 
front 31 right triangle  back 31 a triangle with 1 right angle 
front 32 acute triangle  back 32 a triangle with 3 acute angles 
front 33 obtuse triangle  back 33 a triangle with one obtuse angle 
front 34 congruent  back 34 2 shapes that are the same shape and the same size 
front 35 similar  back 35 2 shapes that are the same shape but not the same size 
front 36 classify  back 36 To arrange in groups, by some property.

front 37 ellipse  back 37 a 2 dimensional shape that resembles a flatten circle

front 38 equiangular  back 38 
front 39 two dimensional  back 39 a shape that has height and width but no depth, Squares, Circles, Triangles, etc are two dimensional objects 
front 40 congruent polygons  back 40 2 polygons that are the same shape and same size 