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Lesson 1

1. Lesson 1

1.6. Explore 2

Mathematics 30-3 Module 5

Module 5: Geometry

 

In the next Try This, you will discover how properties of triangles can be used to determine the angles of triangles.

 

This photograph shows triangular roof trusses.

iStockphoto/Thinkstock

Try This 2

 

A construction worker builds triangular roof trusses. She needs to know the side lengths and interior angles of the trusses that have been built.

  1. Four triangular roof trusses have been built and are drawn in the following table. Complete the table using your knowledge of triangles.

     

    Triangle

    Classify by Angle (acute, obtuse, or right)

    Classify by Side Length (equilateral, isosceles, or scalene)

    Measure of Indicated Angles
    This is a diagram of triangle ABC with each side labelled “8 feet.”

     

     

    ∠A =
    ∠B =
    ∠C =
    This is a diagram of triangle ABC with side AB and side AC labelled “1.5 metres” and angle A labelled “30 degrees.”

     

     

    ∠B =
    ∠C =
    This is a diagram of triangle ABC with side AB labelled “10 feet,” side AC labelled “7 feet,” and side BC labelled “12.2 feet.” Angle A is indicated to be 90 degrees and angle C is labelled “55 degrees.”

     

     

    ∠B =
    This is a diagram of triangle ABC with side AB labelled “9 feet,” side AC labelled “7 feet,” and side BC labelled “16 feet.” Angle A is labelled “115 degrees” and angle C is labelled “31 degrees.”

     

     

    ∠B =

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