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Aim : How do we find the area of polygons?

February 11, 2014. Aim : How do we find the area of polygons? Do Now : 1) Which expression represents the length of fencing that will be needed ? 2) What is the perimeter of the figure shown below, which consists of an isosceles trapezoid and a semicircle in terms of π(pi)?. Do Now.

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Aim : How do we find the area of polygons?

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  1. February 11, 2014 Aim: How do we find the area of polygons? Do Now: 1) Which expression represents the length of fencing that will be needed? 2) What is the perimeter of the figure shown below, which consists of an isosceles trapezoid and a semicircle in terms of π(pi)?

  2. Do Now 1. A garden is in the shape of an isosceles trapezoid and a semicircle, as shown in the diagram below. A fence will be put around the perimeter of the entire garden. Which expression represents the length of fencing that will be needed?

  3. Do Now 2. What is the perimeter of the figure shown below, which consists of an isosceles trapezoid and a semicircle in terms of pi?

  4. Review A designer created a garden, as shown in the diagram below. The garden consists of four quarter-circles of equal size inside a square. The designer put a fence around both the inside and the outside of the garden. Represent the amount of fencing, in yards, that the designer used for the fence in terms of π.

  5. New VocabularyWhat does area mean?

  6. New VocabularyWhat does area mean? The area of a polygon is the number of the square units within.

  7. How to find the Area of polygons and circles Procedure: 1. Use formulas • Square: A = s² or s • s • Rectangle: A = bh or lw • Parallelogram: A = bh • Triangle: A = ½bh • Trapezoid: A = ½h(b1+b2) • Circle: A = (Apple pies are too)

  8. Ex- What is the area of the following rectangle? 4 un. 6 un.

  9. Ex- What is the area of half the rectangle? 4 un. 6 un.

  10. Ex- What is the area of half the rectangle? 4 un. 6 un.

  11. So the area triangle is half a rectangle!

  12. How do we find the area of different polygons? Example 1) Find the area of the square Formula: ______ Example 2) Find the area of the rectangle Formula: ______ 8 in 14 cm 10 cm

  13. 6.6 m Example 3) Find the area of the parallelogram Formula: _______ Example 4) Find the area of the triangle Formula: _______ 3 m 8 ft 5.1 ft 11 ft

  14. Together! Example 5) Find the area of the circle to the nearest tenth. Example 6)Find the area of the circle to the nearest tenth. 5cm 20 mm

  15. Together! Example: Jessica is making a circular table cloth for an art project.  She wants half of the cloth to be a plain colored fabric and half to be a print fabric.  How many square yards of each fabric (to the nearest hundredth of a yard) will she actually be using if the diameter of the cloth is 6 feet?

  16. Key Words/Phrases Perimeter Area Cover • Enclose

  17. Regents Challenge

  18. Practice Time! 1. The radius of a circle is 5 inches. Find the area of the circle. 2. What is the area of a circle whose diameter is 14 centimeters in terms of π?

  19. Practice Time! 3. Find the area of a circle with diameter of 54. 4. A rectangle is 9 inches long and 10 inches wide. Find its area.

  20. Practice Time! 5. The base of the triangle is 12 inches long and the height of the triangle is 12. Find its area. 6. A trapezoid has a base of 4 and 6 yards and has a height of 10 yards. Find its area.

  21. Practice Time! 7. Find the area of a square whose side is 5 inches long. 8. If the area of a square is 20 squared inches. How long is one side of the square?

  22. Practice Time! 9. The area of a circle is 10π. Find the radius and diameter of the circle. 10. If the area of a rectangle is 10 squared units. The width is 5 units. What is the length?

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