Shapes and Sides

 

Angles

Areas

Perimeter

Circles

Triangles

Links

 

Definitions:

Square: A shape with four equal sides

Trapezoid: A four sided figure with two parallel sides.

Rhombus: A four sided figure with two sets of equal sides.

Rectangle: A four sided figure whose opposite sides are equal and parallel.

Pentagon: A five sided figure.

Hexagon: A six sided figure.

Octagon: An eight sided figure.

Decagon: A ten sided figure.

Quadrilaterals: Any four-sided polygon.

These are various shapes.

 


 

Circles and Formulas

Definitions:

Radius: A line segment from the center to the edge of a circle.

Diameter: A line segment from one edge of the circle to the other. Goes through the center of the circle.

Circumference: The distance around a circle.

Center: The middle point in the circle.

Chord: A segment from one point on the circle to another point on the circle. Does NOT go through the center

Perimeter: The combined total of distance around an object.

Formulas: (R = Radius; D = Diameter; C = Circumference)

Formula for Radius: R = D / 2

Formula for Diameter: D = 2 * r

Formula for Circumference: C = pie * d (pie = 3.14)

Formula for Area of a circle: A = pie * r (squared or to the 2nd power)

This is a circle.

 

 

 


 

Angles

Angles can be classified into 4 groups by their angle measures:

This is a picture of angles.

    Complementary angles have a combined measurement of 90 degrees.

This is a picture of complementary angles.

    Supplementary angles have a combined measurement of 180 degrees.

This is a picture of supplementary angles.

 

 

 


 

Triangles

Triangles as classified by their angles:

  • Equiangular triangle: All angles are acute and congruent
  • Acute triangle: All angles are acute
  • Obtuse triangle: One angle is an obtuse angle
  • Right triangle: One angle is a right angle

These are different triangles.

Triangles as classified by their sides:

  • Scalene: No equal sides
  • Isosceles: 2 equal sides
  • Equilateral: 3 equal sides

These are scalene, isosceles, and equilateral triangles.

 

 

 


 

Areas
    • To find the Area of Parallelograms
      • A = area; b = base; h = height
      • Formula: A = b * h

This is the area of parallelogram.

    • To find the Area of a Triangle
      • Multiply 1/2 its base times its height.
      • Formula: A = 1/2 * b * h

This is the area of triangle.

  • To find the Area of a Trapezoid
    • Formula: A = 1/2 (b1 + b2) * h

     

This is the area of trapezoid.

  • To find the Area of a Circle
    • Formula: A = 3.14 * r squared or to the 2nd power

This is the area of circle.

 

 

 


 

Perimeter

 

This is a picture of perimeter.

 

 

 

Links

http://www.mathleague.com/help/geometry/geometry.htm

http://www.math.com/homeworkhelp/Geometry.html

http://www.mathgoodies.com/lessons/toc_vol2.shtm

http://www.gomath.com/geometrycal.html

http://school.discovery.com/homeworkhelp/webmath/

http://www.mathgoodies.com/worksheets/

http://www.mathgoodies.com/

http://www.mathpower.com/funstuff.htm

 

 

This link describes a square. This link describes a rectangle.