b = base

h = height

multiply all 3 numbers

Area of a triangle

Math-Aids.Com

Area and Perimeter FormulasArea and Perimeter Formulas

Triangles - Common
A polygon with three angles and three sides.

a

b

c

h

Area = base x height = bh

1_
2

1_
2

Perimeter = a + b + c

Equilateral Triangles
A Triangle with all three sides of equal length.

s

s

s
Area = x (side) = s

3__
4

2

3__
4

2

Perimeter = 3 x sides = 3 s

Isosceles Triangles
A Triangle with two sides of equal length.

b

a

b
Area = 4b - a

a__
4

22

Perimeter = a + 2 b

Right Triangles
A Triangle with one right angle.

b

a

c
Area =

ba__
2

Perimeter = a + b + c

Square
A Square is a quadrilateral with four equal sides and angles at 90.

o

a

a

Area = a2

Perimeter = 4a

Math-Aids.Com

Area and Perimeter FormulasArea and Perimeter Formulas

Rectangle
A Rectangle is a quadrilateral with four equal angles at 90.

o

w

l

Area = lw

Perimeter = 2(w + l)

Parallelogram
A Parallelogram is a quadrilateral with opposite sides parallel.

a

b

h
Area = bh

Perimeter = 2(a + b)

Rhombus
A Rhombus is a Parallelogram with all sides equal.

a

a

h
Area = ah

Perimeter = 4a

Trapezoid
A Trapezoid is a Quadrilateral with at least one pair of parallel sides.

b1

b2

a1

a2

h
Area =

a1 + a2_____

2
h

Perimeter = a1 + a2 + b1 + b2

Regular n-gon
A Regular Polygon is a polygon for which n sides and angles are equal.

s

a

Area =

1__
2( a n s )

Perimeter = n s