Geometry Guide

Lines planes pointsangles

Point

A dot with a letter

s

Lines

A line that goes on for ever

fs

Line Segment

A straight line

s

m

Ray

One line that goes on for ever

fd

Plane

A flat end that extends

s

d

a

Intersecting

Two lines that cross

Perpendicular

A right angle 90 degrees

Parallel

Two lines that don't cross

Skew

Lanes that are not in the same plane

Acute

A 50 degree angle

Obtuse

A 180 degree angle

Vertex/ Vertice

The middle point

Right

A 90 degree angle

Straight

A straight angle that equals thats 180 degrees

Complementary

If the measure is 90 degree

15

75

Supplementary

If the measure is 180 degrees

100

80

Vertical/ Opposite

Are opposite two lines interesect

r

m

n

p

q

adjacent

Side by side common vertex and ray

s

t

w

d

f

Triangles

ObtuseAcuteRightEquilateralIsoscelesScalene

Obtuse Triangle

The greatest angle is the obtuse that equals 180

Acute Triangle

The greatest angle is an acute angle that equals 180

Right Triangle

The greatest angle is a right angle that equals 180

Equilateral triangle

3 congruent sides

Isosceles Triangle

At least 2 congruent sides

Scalene Triangle

No congruent sides

Perimeter

Add all the sides up

5

5

15

5+5+15=25

Sum of Internal Angles

The sides and the triangles

4 sides and 2 triangles

2 x 180 = 360

Area

Time the base and height

10

20

15

Quadrilaterals

Trapezoid ParallelogramRectangleRhombusSquare

Quadrilateral

A box that makes 4 right angles

Trapezoid

2 set of parallel line

Parallelogram

4 connected sides

Rectangle

Four right angles

Rhombus

Four congruent sides

Square

Congruent sides

Area of a Rectangle

Times the outside then divided by two

25

10

Area of a Square

The outside is times then divided

6

8

Area of a Parallelogram

Times and then divided

Area of a Trapezoid

The outsides are times then divided

9

Circles

Chord diameter sectorradius

Chord

Where you draw a line at the top

Diameter

The middle part of a circle

Arc

A part of a circle named by two rays with common endpoints.

a

b

Radius

The outside of the circle

radius

Sector

A region enclosed by two radii

Circumference

The distance around a circle

6m.

Area of circle

The outside of a circle

Other Polygons

Pentagonhexagonoctangon

Pentagon

It has 5 sides

Hexagon

All sides are congruent

Octogon

It has six sides