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Formulas for Geometry

Formulas for Geometry. Mr. Ryan. Visit www.worldofteaching.com for more free powerpoints. Student Expectations. 6 th Grade 6.4.8A Estimate measurements (including circumference) and evaluate reasonableness of results. 7 th Grade

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Formulas for Geometry

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  1. Formulas for Geometry Mr. Ryan Visit www.worldofteaching.com for more free powerpoints

  2. Student Expectations 6th Grade • 6.4.8A Estimate measurements (including circumference) and evaluate reasonableness of results. 7th Grade • 7.4.9A Estimate measurements and solve application problems involving length (including perimeter and circumference) and area of polygons and other shapes. Free powerpoint template: www.brainybetty.com

  3. 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

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

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

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

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

  8. 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

  9. 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

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

  11. 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 14 20 25 Free powerpoint template: www.brainybetty.com

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

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

  14. 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

  15. 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) 1 2 3 4 2 units (ft, in, m) Free powerpoint template: www.brainybetty.com

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

  17. 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

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

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

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

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

  22. 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

  23. 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) If the radius is 5, then the diameter is 10 Free powerpoint template: www.brainybetty.com

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

  25. 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

  26. • 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

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