POLYGONS

Multi-Sided Figures

First - Some Definitions:

Angles - The intersection between two lines

Right angle- a angle of 90°(90 degrees) also called perpendicular

Types of Polygons:

Triangles = three sides
Quadrilateral = four sides
Pentagon = five sides
Hexagon = six sides
Octagon = eight sides
That's enough of that!!!!

Regular polygons are polygons that have all sides the same length and all of the angles inside the pologon are equal.

TRIANGLES

Three Sided Figures

Some formula's that apply to all triangles:

Area = 1/2 times Base times Height (the height can be the tricky part)

Perimeter = just add together the lengths of all the sides.

Sum of the interior angles = 180° (180 degrees)

Some examples:

Equilateral Triangle (all sides are the same length and all angles are the same-that means it is a "regular polygon")

Area = 1/2 times base times height(h=height,b=base)
Perimeter = sum of the sides = b+b+b = 3b

Isosceles Triangle (two of the sides are equal)

Area = 1/2 times base times height (h=height,b=base)

Perimeter = a+a+b = b+2a

Right Triangle ( has one 90° angle)

Area = 1/2 times Base times Height = 1/2 bh

Perimeter = a+b+h

Acute Triangle ( all of the angles are less than 90°)

Area = 1/2 times base times height = 1/2 bh

Perimeter = a+b+c

Obtuse Triangle ( one of the angles is greater than 90°)

Area and Perimeter - You try it - answer at bottom

QUADRILATERALS

Four Sided Figures

Squares (no ..not mom and dad) All four sides are equal in length and all angles are 90 ° so it is a regular polygon

Area = base times height = s x s = s² {s squared}

Perimeter = s+s+s+s = 4s

Rectangles = (2 pair of equal length sides and all angles are 90°)

Area = base times height = a x b = ab

Perimeter = a+a+b+b = 2a + 2b

Parallelogram ( 2 pairs of equal length sides but none of the angles is 90°)

Area and Perimeter - you try it - answer at bottom

Trapezoid - odd shaped little critter(4 sides and two of them are parallel to each other)

Area = 1/2 times (b+c) times height = 1/2(b+c)h

Perimeter = a+b+c+d

Answers:

Obtuse Triangle:
Area = 1/2 times base times height = 1/2 bh
Perimeter = a+b+c

Parallelogram:
Area = base time height = bh
Perimeter = a+b+a+b = 2a + 2b