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"Perimeter" "Running Laps“ Distance around the outside!

Learn how to find the perimeter of shapes and calculate the area of rectangles, triangles, and parallelograms with detailed examples and formulas. Practice exercises included!

eileenmurphy
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"Perimeter" "Running Laps“ Distance around the outside!

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  1. "Perimeter" "Running Laps“ Distance around the outside!

  2. The perimeter of a figure is the distance around it. To find the perimeter you can add the lengths of the sides.

  3. "Perimeter" is easy with uniform shapes.. but not all shapes are uniform...rectangle! Like this!

  4. Additional Example 1: Finding the Perimeter of a Polygon Find the perimeter of the figure. Add all the side lengths. 2.8 + 3.6 + 3.5 + 3 + 4.3 The perimeter is 17.2 in.

  5. Try This: Example 1 Find the perimeter of the figure. 3.3 in. 3.3 in. Add all the side lengths. 3.3 + 3.3 + 4.2 + 4.2 + 3 The perimeter is 18 in. 4.2 in. 4.2 in. 3 in.

  6. Additional Example 2: Using a Formula to Find Perimeter Find the perimeter P of the rectangle. 12 cm 3 cm P = 2l+ 2w Substitute 12 for l and 3 for w. P = (2 • 12) + (2 • 3) P = 24 + 6 Multiply. P = 30 Add. The perimeter is 30 cm.

  7. How many individual boxes are there here?

  8. Learn to find the area of rectangles, triangles, and parallelograms.

  9. Insert Lesson Title Here Vocabulary area

  10. The area of a figure is the amount of surface it covers. We measure area in square units. Get out your calculators!

  11. A =lw A = 15 •9 A = 135 The area is 135 in2. Additional Example 2: Estimating the Area of a Rectangle Find the area of the figure. Write the formula. 15 in. Substitute 15 for l. 9 in. Substitute 9 for w.

  12. A =lw A = 13 •7 A = 91 Try This: Example 2 Find the area of the figure. Write the formula. 13 in. 7 in. Substitute 13 for l. Substitute 7 for w. The area is 91 in2.

  13. 3 ft. 46 ft. A= 3 x 46 2 A= 138 ft

  14. 3 ft. 46 ft. A= 3 x 46 2 A= 138 ft

  15. 5 cm. A= 5 x 25 25 cm. 2 A=125 cm

  16. You can use the formula for the area of a rectangle to write a formula for the area of a parallelogram. Imagine cutting off the triangle drawn in the parallelogram and sliding it to the right to form a rectangle. The area of a parallelogram = bh. The area of a rectangle = lw. The base of the parallelogram is the length of the rectangle. The height of the parallelogram is the width of the rectangle.

  17. 1 25 5 1 5 1 1 1 1 __ __ __ __ __ ___ __ __ __ 4 4 2 8 8 4 2 8 2 Substitute 2 for b and 1 for h. The area is 3 ft2. A = or 3 A = • A = bh A = 2 •1 Additional Example 3: Finding the Area of a Parallelogram Find the area of the parallelogram. Write the formula. 1 1 ft 4 1 2 ft 2 Multiply.

  18. 1 3 1 1 21 1 1 7 1 __ ___ __ __ __ __ __ __ __ 2 2 2 2 4 2 4 4 2 Substitute 1 for b and 3 for h. 1 1 1 ft 3 ft 2 2 A = or 5 A = • A = 1 •3 A = bh The area is 5 ft2. Try This: Example 3 Find the area of the parallelogram. Write the formula. Multiply.

  19. I made a DELICIOUS peanut butter and jelly sandwich for lunch today. I’m so excited to eat it!!! Dylan came to me crying and said he forgot his lunch! Since I’m so nice, I cut my sandwich diagonally and gave one piece to Dylan and kept one for myself. Who got more of the sandwich??

  20. You can make a square out of two congruent triangles.

  21. If the area of a triangle is HALF the area of the rectangle, what could we use for the formula of a triangle?

  22. New Formula We can pretend the triangle is a rectangle and find the area of the rectangle! Then divide it by two. LW ÷ 2

  23. New Formula We can pretend the triangle is a rectangle and find the area of the rectangle! Then divide it by two. B H 1/2 BH 2

  24. 1 1 1 __ __ __ 2 2 2 A = 13.92 A = (9.6 •2.9) The area is 13.92 cm2. A = (27.84) A = bh Additional Example 4: Finding the Area of a Triangle Find the area of the triangle. Write the formula. Substitute 9.6 for b. Substitute 2.9 for h. Multiply.

  25. 1 1 1 __ __ __ 2 2 2 A = (28.9) A = (8.5 •3.4) A = 14.45 A = bh The area is 14.45 cm2. Try This: Example 4 Find the area of the triangle. Write the formula. 3.4 cm Substitute 8.5 for b. Substitute 3.4 for h. 8.5 cm Multiply.

  26. 41.4 m2 24 ft2 160 in2 35 in2 Insert Lesson Title Here Lesson Quiz Find the area of each figure. 1. 2. 3. What is the area of a parallelogram with base 16 in. and height 10 in.? 4. What is the area of a triangle with base 10 in. and height 7 in.? 4.5 m 9.2 m

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