Geometry

Lesson 10

Math

Unit 6

7th Grade

Lesson 10 of 21

Objective


Solve problems involving area and circumference of two-dimensional figures (Part 1).

Common Core Standards


Core Standards

  • 7.G.B.4 — Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.
  • 7.G.B.6 — Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms.

Foundational Standards

  • 6.G.A.1

Criteria for Success


  1. Know and use the formulas for area and circumference of a circle.
  2. Given the circumference of a circle, determine the area of the circle.
  3. Find the area and perimeter/circumference of composite shapes, including shapes composed of circles, semi-circles, quadrilaterals, and triangles.

Tips for Teachers


  • Lessons 10 and 11 engage students in finding area and circumference/perimeter measurements of different geometric shapes including circles, quadrilaterals, and triangles. The Problem Set Guidance includes a variety of problems that range in difficulty and time required. 
  • Students engage in MP.1 and MP.7 as they make sense of complex geometric figures, looking for significance of shapes and measurements within the structure of the diagram, and looking for entry points to solve the problem. Support students by asking questions about what they observe in the diagrams and what initial strategy ideas they have.
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Anchor Problems


Problem 1

The circumference of a circle is $$32\pi$$ cm. What expression represents the exact area of the circle? If needed, draw a diagram to assist you.

Guiding Questions

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Problem 2

Find the area and perimeter of the colored part of each figure below. The figures are composed of small squares with side length 1 unit and curves that are an arc of a circle. 

a.   

b.   

Guiding Questions

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References

Illustrative Mathematics Designs

Designs, accessed on March 10, 2018, 12:59 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Modified by Fishtank Learning, Inc.

Problem 3

A semi-circle with a diameter of 6 cm sits on top of an isosceles trapezoid. Find the area of the entire figure.

Guiding Questions

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Problem Set

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Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

Target Task


A semi-circle is connected to an isosceles triangle. The radius of the semi-circle is 2 inches, and the height of the triangle is 6 inches. Find the area of the composite figure. 

Student Response

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Additional Practice


The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

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Lesson 9

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Lesson 11

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Angle Relationships

Topic B: Circles

Topic C: Building Polygons and Triangles

Topic D: Solid Figures

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