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Published byShonda Day Modified over 5 years ago

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Intro to Geometry in 2D These are your notes for Area of 2 Dimensional figures…Write & Draw EVERY detail as if I was at the front of class. Write down any questions you may have, ask the substitute, or a neighbor!

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**HAVE YOU NOT GOT OFF THIS SLIDE YET?**

COME ON! GET MOVING GUYS! By:Jeffrey McAven

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**Lets look at 2 Dimensional Shapes and their Formulas**

Triangles (3 sides) Quadrilaterals (4 sides) Polygons-3 or more sides, must be closed, no curved or overlapping sides

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**Polygons- Any closed shape made up of straight lines.**

We have already talked about Triangles and Quadrilaterals, lets look at some more common polygons. Pentagon (5 sides) Hexagon (6 sides) Heptagon (7 sides) Octagon (8 sides) Nonagon (9 sides) Decagon (10 sides) You do not need to know the formulas for these but should be able to recognize them.

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Perimeter To find the perimeter of any polygon all you need to do is add the sides.

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Perimeter

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Quadrilaterals A Quadrilateral is any four sided figure. Lets look at the most common. Square – All Sides and Angles same A=s2 or A=base(height) Rectangle – All Angles are the same and parallel sides are the same measure A=base(height)

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**Squares and Rectangles**

Area of Rectangle: A = bh Area of Square: A = s² s A = s² b h A = bh Example: Example: 12 5 6 A = 6² = 36 sq. units A = 12 x 5 = 60 sq. units

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**Quadrilaterals Parallelogram – Parallel side are the same A=bh**

Rhombus A=bh Trapezoid

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**Parallelograms & Rhombus**

Area of Parallelogram: A = b(h) Area of Rhombus: A = b(h) Example: h b Example: 6 9 A = 9 x 6 = 54 sq. units

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Trapezoids Or The height (h) is the distance between the two bases b1 & b2, perpendicular to each base h b1 b2

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Triangles A Triangle is a three sided figure. All triangles have the same Area formula or

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**Triangles Right Triangle – Has one angle 90○**

Acute Triangle – Every angle is less than 90○ Obtuse Triangle –Has one angle more than 90○

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Triangles Equilateral Triangle – All angles and sides are the same measure Isosceles Triangle – Two sides are the same and two angles are the same Scalene Triangle – All sides and angles are different

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Triangles Or h is the distance from a vertex of the triangle perpendicular to the opposite side. h b

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Circles Circumference of a circle is the distance around the outside of the circle. The formula is C=2πr or C= πd Area formula for a circle is A= πr2

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Area of a Circle Area formula for a circle is A= πr2

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**Circumference of a Circle**

Circumference formula for a circle is or

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**Area of Composite Figures**

The area of a composite figure is the sum of all of its non-overlapping parts. 8 10 12 4 14 A = ½(8)(10) A= 40 A = (12)(10) A= 120 A = (4)(8) A=32 A = (14)(8) A=112 Area = = 304 sq. units

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**Answers: 140cm2 56cm2 180cm2 168cm2 132cm2 240cm2 330cm2 72cm2 225cm2**

9 8 10 14cm 12cm 18cm 9cm 16cm 12cm 20cm 12 11 8cm 14cm 13 25cm 15cm 14cm 15cm 12cm 16cm 12cm

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**Try these on your own!!! 2 3 1 9cm 12cm 13cm 4 8cm 15cm 4cm 15cm 9cm 6**

7 9cm 12cm 11cm 12cm 15cm 14cm 40cm 12cm 9 8 10 14cm 8cm 8cm 20cm 18cm 8cm 40cm 12 11 24cm 18cm 13 35cm 25cm 14cm 15cm 12cm 36cm 22cm

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