Determine the relationship between the area and radius of a circle and use it to solve problems.
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Lessons 8 and 9 focus on the relationship between a circle’s area and its radius. In Lesson 8, students determine this relationship and the formula that represents it. In Lesson 9, students will solve real-world and mathematical problems involving area.
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Use the centimeter grid to find an approximate area of the circle. Explain why your approximation is reasonable.
Use this applet from Academo, Area of a circle (Rearrangement Method) to informally derive the relationship between the area of a circle and its circumference
Start with a small number of sectors or wedges of the circle and then slowly increase the number. Click “rearrange” after each number. Ask:
Area of a Circle (Rearrangement Method) is made available by Academo. © Academo.org 2016. Accessed March 10, 2018, 11:26 a.m..
Use the relationship between area and radius to solve the two problems below.
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The following resources include problems and activities aligned to the objective of the lesson that can be used to create your own problem set.
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A circle is divided into 16 equal wedges, as shown below. Explain or show how you can rearrange the pieces to determine the area of the circle.
Find the area of a circle that has a radius of 5 inches.
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