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

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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.

Triangles Classified by their sides Equilateral Triangle -all 3 sides equal in length -all 3 angles equal in measure

Triangles Classified 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 KL M

Triangles Classified by their sides Scalene Triangle -0 sides equal in length

Triangles Classified by their angles Acute Triangle -all 3 angles acute 60° The sum of the angles in a triangle equals 180°.

Triangles Classified by their angles Obtuse Triangle obtuse angle -2 acute angles The sum of the angles in a triangle equals 180°. 120° 35° 25°

Triangles Classified by their angles Right Triangle 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° The sum of the angles equals 360°. 90 ° + 90 ° + + = 360 ° 90 ° x 4 = 360 °

Rectangle 4 right (90°) angles Opposite sides parallel Opposite sides equal in length 90° The sum of the angles equals 360°. 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 ° + = 360 ° 80 ° 100 °

Parallelogram Opposite sides parallel The sum of the angles equals 360°. 80 ° + 80 ° + 100 ° + = 360 ° 80 ° 100 °

Trapezoid Has one pair of parallel sides The sum of the angles equal 360°. 80 ° + 80 ° + 100 ° + = 360 ° 100 ° 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°  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° 80°  1 = ____ 100°  1

Find the missing angle measurement in the triangle. 78°  1  1 = ____ 24°

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