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Basic Geometry

Basic Geometry

At a Glance - Area Formulas

Let's go over these formulas one more time.

Formulas for different shapes:

Area of Rectangle = Base × Height

Area of Triangle = ½(Base × Height)

Area of Parallelogram = Base × Height

Area of Trapezoid = ½(Base1 + Base2) × Height

Area of Circle = πr2

Area of a Parallelogram

area = b x h

Area of a Triangle

Area of a Trapezoid

area of trapezoid  = 1/2(b1 +b2) x h

Area of a Circle

area = pi * r ^ 2

Area of a Regular Polygon

area = 1/2 x a x p

a = apothem

P =  perimeter

This is a regular hexagon with sides of 3.4 cm and an apothem of 2.9 cm.

This is a regular quadrilateral, or square, with sides of 4.4 cm and an apothem of 2.2 cm.

You can compare this to multiplying base times height:

Exercise 1

Find the area of a circle with a diameter of 3 inches.

Exercise 2

Find the area of:

pentagon 5.1 side length

Exercise 3

Find the area of:

trapezoid with height 3.6cm

Exercise 4

This isosceles right triangle:

Isosceles Right Triangle (#4)

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