1. Basic Geometric Terms

2. Geometry The study of the size and shape of things
It is essential to recognize geometry that exists within objects for the purpose of creating solid models or multiview drawings

3. Angles Acute Angle Obtuse Angle Right Angle Vertex
Measures less than 90°
Obtuse Angle
Measures more than 90°
Right Angle
Measures exactly 90°
Vertex
Point at which two lines of an angle intersect
Vertex

4. Circle Radius Diameter Circumference Chord
Distance from the center of a circle to its edge
Diameter
Distance across a circle through its center
Circumference
Distance around the edge of a circle
Chord
Line across a circle that does not pass at the circle’s center

5. Circle Has 360° Quadrant Concentric One fourth (quarter) of a circle
Measures 90°
Concentric
Two or more circles of different sizes that share the same center point
90°

6. Triangles Equilateral Isosceles Scalene
All three sides are of equal length and all three angles are equal
Isosceles
Two sides are of equal length
Scalene
Sides of three different lengths and angles with three different values

7. Triangles HYPOTENUSE Right Triangle Hypotenuse
One of the angles equals 90°
Hypotenuse
The side of a right triangle that is opposite the 90° angle
HYPOTENUSE

8. Quadrilaterals Square Rectangle Trapezoid
Four equal sides and all angles equal 90°
Rectangle
Two sides equal lengths and all angles equal 90°
Trapezoid
Only two sides are equal length

9. Quadrilaterals Rhombus Rhomboid
All sides are equal length and opposite angles are equal
Rhomboid
Opposite sides are equal length and opposite angles are equal

10. Regular Polygons Pentagon Hexagon Octagon Five sided polygon
Six sided polygon
Octagon
Eight sided polygon

11. Regular Polygons Heptagon Nonagon Decagon Dodecagon
Seven sided polygon
Nonagon
Nine sided polygon
Decagon
Ten sided polygon
Dodecagon
Twelve sided polygon 11

12. Geometric Terms Circumscribe Inscribe
Process of creating a polygon that fully encloses a circle and is tangent to all of the polygons sides
Inscribe
Process of creating a polygon that is fully enclosed by a circle at its corners

13. Regular Polygons Distance across flats Distance across corners
Measurement across the parallel sides of a polygon
Circumscribed
Distance across corners
Measurement across adjacent corners of a polygon
Inscribed

14. Geometric Terms Bisect Tangent Divide into two equal parts
A line and arc, or two arcs that touch each other at one point only

15. Geometric Terms Parallel Perpendicular
Two or more lines that are always the same distance apart
Perpendicular
Two lines that are at a 90° angle

16. Geometric Symbols Angle Triangle Radius Diameter Parallel
Perpendicular
Square
Centerline R C L