Area and Perimeter Formulas
Triangles - Common
A polygon with three angles and three sides.
a
c
h
1
1
Area = _2 base x height = _2 bh
Perimeter = a + b + c
b
Equilateral Triangles
A Triangle with all three sides of equal length.
s
s
3
2
3
2
__
Area = __
x
(side)
=
s
4
4
Perimeter = 3 x sides =
3s
s
Isosceles Triangles
A Triangle with two sides of equal length.
b
b
a
Area = __
4
2
2
4b - a
Perimeter = a + 2 b
a
Right Triangles
A Triangle with one right angle.
b
c
ba
Area = __
2
Perimeter = a + b + c
a
Square
o
A Square is a quadrilateral with four equal sides and angles at 90.
2
Area = a
a
Perimeter = 4a
a
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Area and Perimeter Formulas
Rectangle
o
A Rectangle is a quadrilateral with four equal angles at 90.
Area = ab
a
Perimeter = 2(a + b)
b
Parallelogram
A Parallelogram is a quadrilateral with opposite sides parallel.
a
h
Area = bh
Perimeter = 2(a + b)
b
Rhombus
A Rhombus is a Parallelogram with all sides equal.
a
h
Area = ah
Perimeter = 4a
a
Trapezoid
A Trapezoid is a Quadrilateral with at least one pair of parallel sides.
a2
b1
h b2
a1 + a2
Area = _____
h
2
Perimeter = a1 + a2 + b1 + b2
a1
Regular n-gon
A Regular Polygon is a polygon for which n sides and angles are equal.
a
1
Area = __
(a n s)
2
Perimeter = n s
s
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