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## basic concepts area and perimeter

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**basic concepts**area and perimeter**Find the area of a rectangle**whose dimensions are**Find the area of a rectangle**whose dimensions are 5 3 3 5**Find the area of a rectangle**whose dimensions are 5 3 3 5**Find the area of a rectangle**whose dimensions are 5 3 3 15 square units 5 It takes 15 1x1 tiles to cover the rectangle.**Find the area of a rectangle**whose dimensions are 5 3 W 3 15 square units 5 L It takes 15 1x1 tiles to cover the rectangle. Area = Length x Width A = LW**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 L**“measure”**Find the perimeter of a rectangle whose dimensions are 5 3 W 3 5 L**“around”**Find the perimeter of a rectangle whose dimensions are 5 3 W 3 5 L**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 5 L**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 + 3 5 L**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 + 3 + 5 5 L**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 + 3 + 5 + 3 5 L**Find the perimeter of a rectangle**whose dimensions are 5 3 W 3 5 + 3 + 5 + 3 5 L Perimeter = Length + Width + Length + Width P = 2L + 2W**The DIAMETER is the**measure across the circle**The DIAMETER is the**measure across the circle through the center**The DIAMETER is the**measure across the circle through the center The RADIUS is the measure from the center to any point on the circle The diameter = 2 times the radius d = 2r**The diameter fits 3 times plus**a little extra. The number is the exact number of “diameters” needed to complete the circle. is approximately 3.14**The measure around the circle (perimeter) is called the**circumference. The diameter fits 3 times plus a little extra. The number is the exact number of “diameters” needed to complete the circle. is approximately 3.14**The measure around the circle (perimeter) is called the**circumference. The circumference = times the diameter. C = d The diameter fits 3 times plus a little extra. The number is the exact number of “diameters” needed to complete the circle. is approximately 3.14**The are of a circle is the number of**square units needed to fill the circle. The following formula gives the area of a circle: A = r 2 example: A circle whose radius is 3 units has area 9 28.26 square units <a href = http://www.education2000.com/demo/demo/botchtml/areacirc.htm ></a> Check the web page above to see a visual proof of the area formula**The circumference of the circle is 10 **What is the area of the shaded region?______**The circumference of the circle is 10 **What is the area of the shaded region?______ C = d d = 10 r = 5 10**The circumference of the circle is 10 **What is the area of the shaded region?______ 10 the area of the square is 100**The circumference of the circle is 10 **What is the area of the shaded region?______ 5 10 - the area of the square is 100 the area of the circle is 25 **The circumference of the circle is 10 **What is the area of the shaded region?______ 5 (100 – 25 ) square units 100 – 78.5 = 21.5 square units 10 - the area of the square is 100 the area of the circle is 25