This document provides an overview of common geometry formulas for calculating perimeter and area of different shapes. It explains that perimeter is calculated by adding up the lengths of all sides of a shape, and area refers to the total space within a shape's boundaries. Common formulas are provided for squares, rectangles, triangles, circles, and other shapes. The document seeks to alleviate fears about geometry formulas and emphasizes recognizing which formula to apply to different shapes.

1. Formulas for Geometry

2. Don ’ t Get Scared!!! Evil mathematicians have created formulas to save you time. But, they always change the letters of the formulas to scare you! Free powerpoint template: www.brainybetty.com

3. Perimeter Any shape ’ s “ perimeter ” is the outside of the shape…like a fence around a yard. Free powerpoint template: www.brainybetty.com

4. Perimeter To calculate the perimeter of any shape, just add up “ each ” line segment of the “ fence ” . Free powerpoint template: www.brainybetty.com

5. Perimeter Triangles have 3 sides…add up each sides length. Free powerpoint template: www.brainybetty.com 8 8 8 8+8+8=24 The Perimeter is 24

6. Perimeter A square has 4 sides of a fence Free powerpoint template: www.brainybetty.com 12 12 12 12 12+12+12+12=48

7. Perimeter Sometimes, problems may only give you two measurements for a square or rectangle. No problem…use the formula for squares/rectangles (only!) Free powerpoint template: www.brainybetty.com

8. Remember Squares ALL sides are equal…so if they give you one side, you know ALL the sides Length=the Largest side If they “ leave ” numbers out, they are equal to their opposite side. If they give you the bottom of a square/rectangle type shape then the top is the same Free powerpoint template: www.brainybetty.com

9. The Same!! If the bottom is 15…the top is… Free powerpoint template: www.brainybetty.com 15

10. Square/Rectangle Formula Perimeter=2(Length+Width) P= 2(25+14) P=2(20+20) P= 50+28 P=40+40 P= 78 P=80 Free powerpoint template: www.brainybetty.com 14 25 20

11. Other shapes Just add up EACH segment Free powerpoint template: www.brainybetty.com 10 8 sides, each side 10 so 10+10+10+10+10+10+10+10=80

12. Odd shapes Count ALL sides Remember if one side blank, it ’ s equal to its opposite Free powerpoint template: www.brainybetty.com 25 15 5 25+25=50 (for Length) 15+5+15+5=40 (for Width) Perimeter=90

13. Area Area is the ENTIRE INSIDE of a shape It is always measured in “ squares ” (sq. inch, sq ft) Free powerpoint template: www.brainybetty.com

14. AREA Square units means that “ that ” many squares fit inside that shape (if measured in feet…it ’ s feet…if meters…it ’ s meters. In this example the area is 4 square units…note 4 squares fit) Free powerpoint template: www.brainybetty.com 1 2 units (ft, in, m) 2 3 4

15. Area of Squares/Rectangles Length x Width=Area Free powerpoint template: www.brainybetty.com 2 Length(2) xWidth(2) = 4 square units

16. Parallelogram Area Same idea as squares & rectangles, but they change the words to Base (length:bottom of shape) and height (width) Free powerpoint template: www.brainybetty.com

17. Parallelogram Area Area=Base x Height (Area=length x width) Free powerpoint template: www.brainybetty.com BASE (length) Height (width) 8 5 Base 8 x Height 5 = Area 40 The diagonal line is NOT the height!!!

18. REAL formula for area of squares Area= S^2 Area= Side x Side (side squared) (just a different way of saying length x width) Free powerpoint template: www.brainybetty.com Side one Side two

19. Different Names/Same idea Length x Width = Area Side x Side = Area Base x Height = Area Free powerpoint template: www.brainybetty.com

20. Area of a Triangle ½ Base x Height = Area (It ’ s ½ because ½ of the “ square ” is missing) Free powerpoint template: www.brainybetty.com Base Height Height Base 8 5 ½ Base x Height = Area ½ (8) x 5 = Area 4 x 5 = 20

21. Area of a Circle Pi= 3.14 Radius: from center (origin) of circle to ANY side Area= pi x (Radius x Radius) Free powerpoint template: www.brainybetty.com

22. Circumference of a Circle Perimeter/Circumference = pi x diameter Pi is always 3.14 Circumference is a fancy name for perimeter The diameter is a line from one side to the other side of a circle through its origin (It ’ s twice the radius) Free powerpoint template: www.brainybetty.com If the radius is 5, then the diameter is 10

23. Area of a circle Area = piR^2 Pi = 3.14 and R=Radius Free powerpoint template: www.brainybetty.com Radius 5 Area=3.14 x (5 x 5) Perimeter = 3.14 x 10

24. You ’ re Done Squares, rectangles and parallelograms area are almost the same (LxW) Triangles are ½ cause your missing ½ Circles have fancy names, but just follow the formula Free powerpoint template: www.brainybetty.com

25.  For most tests you will have the formulas given to you. Just remember which one to use for which shape and you ’ ll do fine. Free powerpoint template: www.brainybetty.com