The mathematical study of the properties, measurements, and relationships of points, lines, planes, surfaces, angles, and solids.

Geometry

Lines of Symmetry

• A line that divides a figure into two halves that are reflections of each other.

Transformations

• Reflection

• Rotation

• Translation

Two-Dimensional Figures

Polygons

•A simple closed figure formed by 3 or more sides.

•The number of sides determines the name of the polygon.

Regular Polygons

•A regular polygon is a polygon with all sides congruent and all angles congruent.

Triangles

•A polygon with 3 sides and 3 angles.

•Triangles can be classified by the length of their sides.

•Triangles can be classified by the kind of angles.

TrianglesClassified by their sides

•Equilateral Triangle

-all 3 sides equal in length

-all 3 angles equal in measure

TrianglesClassified by their sides

•Isosceles Triangle

-2 sides are congruent

-the two angles opposite the congruent sides, angles K and L, are the base angles

-the base angles are congruent

K L

M

TrianglesClassified by their sides

•Scalene Triangle

-0 sides equal in length

TrianglesClassified by their angles

•Acute Triangle

-all 3 angles acute

60°

60° 60°

The sum of the angles in a triangle equals 180°.

TrianglesClassified by their angles

•Obtuse Triangle

-1 obtuse angle

-2 acute angles

The sum of the angles in a triangle equals 180°.

120° 35°

25°

TrianglesClassified by their angles

•Right Triangle

-1 right (90°) angle

-2 acute angles

90°

60°

30°

The sum of the angles in a triangle equals 180°.

Quadrilaterals• A polygon with

4 sides.• Some special

quadrilaterals include:

• Square• Rectangle• Parallelogram• Rhombus• Trapezoid

Square

• 4 right (90°) angles

• Opposite sides parallel

• All sides equal in length

90°90°

90° 90°

• The sum of the angles equals 360°.

90°+ 90° + 90° + 90° = 360°

90° x 4 = 360°

Rectangle

• 4 right (90°) angles

• Opposite sides parallel

• Opposite sides equal in length

90°90°

90° 90°

• The sum of the angles equals 360°.

90°+ 90° + 90° + 90° = 360°

90° x 4 = 360°

Rhombus

• Opposite sides parallel

• All sides equal in length

• The sum of the angles equals 360°.

80°+ 80° + 100° + 100° = 360°

80°

80° 100°

100°

Parallelogram

•Opposite sides parallel

•The sum of the angles equals 360°.

80°+ 80° + 100° + 100° = 360°

80°

80° 100°

100°

Trapezoid

•Has one pair of parallel sides

•The sum of the angles equal 360°.

80°+ 80° + 100° + 100° = 360°

100°100°

80°80°

Compare a rectangle and a parallelogram.

Are alike because:• opposite sides

parallel• opposite sides congruent

• four sides

Are different because:• rectangles have

four right angles

Find the missing angle measurement in the

quadrilateral.

80°

100° 100°

1 = ____ 80°

1

Find the missing angle measurement in the triangle.

90°

60° 1 = ____ 30°

1

Find the missing angle measurement in the

quadrilateral.

90°

90° 80° 1 = ____ 100°

1

Find the missing angle measurement in the triangle.

78° 78°

1 1 = ____ 24°