Geometry Vocabulary Topic Polygon Vocabulary Meaning Closed figure with 3 or more sides Example
Types of polygons
1. Quadrilateral
4-sided polygon
2. Pentagon
5-sided polygon
3. Hexagon
6-sided polygon
4. Heptagon
7-sided polygon
5. Octagon
8-sided polygon
6. Nonagon
9-sided polygon 10-sided polygon
7. Decagon
Topic Types of Quadrilate ral
Vocabulary
Meaning
Example
1. Parallelogram A quadrilateral with 2 pairs of parallel sides 2. Square A quadrilateral with 4 right angles and 4 congruent sides 3. Rectangle A quadrilateral with 4 right angles 4. Rhombus A quadrilateral with 4 congruent sides A quadrilateral with exactly 1 pair of parallel sides A quadrilateral with exactly two different pairs of congruent adjacent sides. Have at least one point going in. Have all points going out
5. Trapezoid
6. Kite
Concave Polygons
Convex Polygons
Lines etc
Line
No end points they extend forever in two directions One end point they extend forever in one direction. Two end points they have ends in two directions.
The symbol is AB. In words - line AB. A B
Ray B A Segment B A
The symbol is AB. In words ray AB (Looking at the vocabulary column)
The symbol is AB. In words segment AB. (Looking at the vocabulary column)
Topic
Vocabulary Plane
P
Meaning No edges they extend forever in two directions. Divides or separates an object in 2 or half.
Example The symbol is P. In words - plane P. (Looking at the vocabulary column)
Bisector
Angle bisector
Perpendicular bisector Triangle (side names) Scalene No equal sides
Isosceles
Two equal sides
Equilateral
Three equal sides
Triangle (angle names)
Acute
All angles less than 90
Topic
Vocabulary Right
Meaning One angle equals 900
Example
Obtuse
One angle more than 900
Parallel Lines
Transversal
Crossing or intersecting
What a. b. c. d. e. f. g. h.
is the intersection of: 2 lines = point 2 rays = point or segment 1 line and 1 plane = point or line 2 planes = line 3 planes = point or line 2 segments = point 1 line and 1 ray = point or ray 1 plane and 1 ray = point or ray
Angles
Corresponding angles (1 angle is outside, 1 angle is inside)
Are in matching positions compared to the parallel lines and the transversal.
A and E, G and B, F and C Alternate angles a. Alternate interior angles Are between the parallel lines and diagonally opposite. Are outside the parallel lines and diagonally opposite. (Using the diagram above) D and F, E and B
(Using the diagram above) H and C, A and G
b. Alternate
exterior angles Vertical angles
Are opposite each other on a pair of crossed lines
(Using the diagram above) A and B, C and D, E and G, F and H
Topic
Vocabulary Consecutive interior angles
Meaning Are between the parallel lines and on the same side of the transversal.
Example
Consecutive exterior angles
Are outside the parallel lines and on the same A and H, G and C side of the transversal. Equal
D and E, F and B (Use the above diagram)
Congruent
A and B are congruent G and B are congruent C and H are congruent E and B are congruent Supplementary angles Angles with a sum of 1800 Angles with sum equals to 900
Complementary angles
Supplementary angles F & I, L & H, J & G
Complementary angles D & C, C & I Polygon Angles 1. Sum of interior angles in a No. of sides minus 2 times 1800
(no. of sides 2) x 1800
Decagon (10-sided polygon) (10 2) x 1800 = 1,440 Therefore, the sum of interior angles is 1,440 (10 2) x 1800 = 1,440 = 144 10 10 Therefore, the measurement of interior angles is 144
2. Measurement (size) of interior angles
(no. of sides 2) x 1800 no. of sides
True/False question on properties of polygon
1. State first the True or False. Explain. definition of the second A kite is an equilateral polygon. quadrilateral. 2. Check if the definition fits 1. Equilateral has four equal the first sides polygon. Quadrilateral has four sides 3. If yes then, 2. A kite has 2 different pairs its True. of equal adjacent sides If not then, 3. False its False. 4. False, because a kite does 4. Statement not have four equal sides. Statement format: True/False, because the _________(state the first polygon) has/does not have _________ (state the definition of the second polygon).
