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J ournal Chapter 9 and 10

J ournal Chapter 9 and 10. Majo Díaz-Duran. areas of a square, rectangle, triangle, parallelogram, trapezoid, kite and rhombus:. examples. find the area of a composite figure. Explain what a composite figure is. To find the area you need to break it into individual pieces.

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J ournal Chapter 9 and 10

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  1. Journal Chapter 9 and 10 Majo Díaz-Duran

  2. areas of a square, rectangle, triangle, parallelogram, trapezoid, kite and rhombus:

  3. examples

  4. find the area of a composite figure. Explain what a composite figure is • To find the area you need to break it into individual pieces. • A composite figure is- any figure made up from 2 or more polygons/circles.

  5. Examples: By adding: By Subtracting:

  6. area of a circle: You can use the circumference of a circle to find the are Circumference: 2πr Area: πr2

  7. Examples: The diameter of a circle is 8 centimeters. What is the area? D=2r 8 cm = 2r 8 cm ÷ 2 =r r = 4 cm A=πr2 A= π(4 cm)2 A= 50.24 cm2 The radius of a circle is 3 inches. What is the area? A=πr2 A= π(3 in)2  A= π(9 in2) A= 28.26 in2

  8. what a solid is: • A three dimensional figure, can be made up of flat or curved surfaces, each flat surfaces is called a face, an edge is the segment that is the intersection of two faces, a vertex is the point that is the intersection of three or more faces.

  9. Examples:

  10. find the surface area of a prism. What is a prism? Explain what a “Net” is • A prism is formed by two parallel congruent polygonal faces called bases connected by faces that are parallelograms. The surface area of a prism = right prism with lateral area(L) and base area(B) L + 2B. • A net is a diagram of the surfaces of a three-dimensional figure that can be folded to form the three-dimensional figure

  11. Examples: Net: Pyramid

  12. find the surface area of a cylinder • A cylinder is formed by two parallel congruent circular vases and a curved surface that connects the bases. • Surface Area of a Cylinder = 2 πr2 + 2πrh

  13. Examples: Find the surface area of a cylinder with a radius of 2 cm, and a height of 1 cm S=2pir2+2pirh S=2pi22+2pi(2)(1) S=6.28(4)+6.28(2) S=25.12+12.56 Surface area = 37.68 cm2

  14. find the surface area of a pyramid: • A pyramid is formed by a polygonal base and triangular faces that meet at a common vertex • Lateral area(L) and base area(B) is L+B or P(perimeter)l +B

  15. Example: a square pyramid with a base that is 20 m on each side and a slant height of 40 m Find the surface area of the base and the lateral faces. Base: A=s2 or (20)2 A=400 SA=400+4(400) SA=2000 m2

  16. find the surface area of a cone. • A cone is formed by a circular base and a curved surface that connects the base to a vertex. • lateral are L and Base are B L +B or πrl+πr2

  17. Examples: a cone with a radius of 4 cm and a slant height of 12 cm: SA=pir2+pirL SA=pi(4)2+pi(4)(12) SA=50.3 +150.8 SA =201.1 cm2

  18. find the volume of a cube • The volume of a cube is (length of side)3.

  19. Examples: Example #2 Find the volume if the length of one side is 2 cm V = 23 V = 2 × 2 × 2 V= 8 cm3 Example #3: Find the volume if the length of one side is 3 cm V= 33 V = 3 × 3 × 3 V = 27 cm3

  20. Cavalieri’s principle • If two objects have the same cross sectional area and the same height they have the same volume.

  21. examples

  22. find the volume of a prism • Base area (B) and height (h) is V= Bh

  23. Examples: What is the volume of a prism whose ends have an area of 25 in2 and which is 12 in long: Answer: Volume = 25 in2 × 12 in = 300 in3

  24. find the volume of a cylinder • With base are (B) radius ( r) and height h is V: Bh or V= πr2h

  25. Examples: What is the volume of the cylinder with a radius of 2 and a height of 6? Volume= Πr2h Volume = Π2(6) = 24Π

  26. find the volume of a pyramid • Base area (B) and height(h) V= 1/3Bh

  27. examples A square pyramid has a height of 9 meters. If a side of the base measures 4 meters, what is the volume of the pyramid? Since the base is a square, area of the base = 4 × 4 = 16 m2 Volume of the pyramid = (B × h)/3 = (16 × 9)/3 = 144/3 = 48 m3 A rectangular pyramid has a height of 10 meters. If the sides of the base measure 3 meters and 5 meters, what is the volume of the pyramid? Since the base is a rectangle, area of the base = 3 × 5 = 15 m2 Volume of the pyramid = (B × h)/3 = (15 × 10)/3 = 150/3 = 50 m3

  28. find the volume of a cone • Base area (B), radius ( r ) and height(h) v= 1/3Bh or v= 1/3πr2h

  29. Examples: Calculate the volume if r = 4 cm and h = 2 cm V= 1/3 × pi× 42 × 2 V= 1/3 × pi× 16 × 2 V = 1/3 ×pi× 32 V= 1/3 × 100.48 V = 1/3 × 100.48/1 V= (1 × 100.48)/(3 × 1) V= 100.48/3 V = 33.49 cm3 Calculate the volume if r = 2 cm and h = 3 cm V = 1/3 × pi× 22 × 3 V= 1/3 × pi× 4 × 3 V = 1/3 × pi× 12 V = 1/3 × 37.68 V = 1/3 × 37.68/1 V = (1 × 37.68)/(3 × 1) V = 37.68/3 V= 12.56 cm3

  30. find the surface area of a sphere • surface area = 4πr2

  31. examples Find the surface area of a sphere with a radius of 6 cm SA = 4 × pi × r2 SA = 4 × pi × 62 SA = 12.56 × 36 SA = 452.16 Surface area = 452.16 cm2 Find the surface area of a sphere with a radius of 2 cm SA = 4 × pi × r2 SA = 4 × pi × 22 SA = 12.56 × 4 SA = 50.24 Surface area = 50.24 cm2

  32. find the volume of a sphere • V= 4/3πr3

  33. Examples: If r = 300 mi (the moon), then the volume would be
  V = 4πr3/3 = 4(pi)(300 mi)3/3 = 4(pi)(27,000,000 mi3)/3 = 113,040,000 mi3. If r = 4 cm (a marble), then the volume would be
  V = 4πr3/3 = 4(pi)(4 cm)3/3 = 4(pi)(64 cm3)/3 = 267.9 cm3

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