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This chapter covers the essential concepts of calculating the areas of parallelograms and triangles. It introduces key terminology, such as base and height, and presents theorems for determining areas: the area of a rectangle, parallelogram, and triangle. The chapter includes step-by-step instructions on finding the area of these shapes and examples of how to solve for missing dimensions. By mastering these concepts, learners will build a strong foundation in geometry, essential for future mathematical applications.
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Chapter 10:Area Section 10-1: Area of Parallelograms and Triangles
Objectives: • To find the area of a parallelogram. • To find the area of a triangle.
Vocabulary • Base of a Parallelogram • Altitude of a Parallelogram • Height of a Parallelogram • Base of a Triangle • Height of a Triangle
Theorem 10-1:“Area of a Rectangle” • The area of a rectangle is the product of its base and its height. A = bh height base
Theorem 10-2:“Area of a Parallelogram” • The area of a parallelogram is the product of its base and its height. A = bh height base
Parts of a Parallelogram • A base of a parallelogram is any of its sides. • The corresponding altitude is a segment perpendicular to the line containing that base, drawn from the side opposite that base. • The height is the length of the altitude.
Finding the Area of a Parallelogram • Find the area of the parallelogram:
Finding the Area of a Parallelogram • Find the area of the parallelogram:
Finding a Missing Dimension • Find the value of x. x 3 4 8
Theorem 10-3:“Area of a Triangle” • The area of a triangle is half the product of the base and the corresponding height.
Parts of a Triangle • A base of a triangle is any of its sides. • The corresponding height is the length of the altitude to the base.
Finding the Area of a Triangle • Find the area of the triangle: 9 16
Finding the Area of a Triangle • Find the area of the triangle: 5 6