Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
4. Constructing Polygons
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Exercise 28 Page 387

Use a protractor to draw the given angles.

One, see solution.

Practice makes perfect

We want to determine whether we can construct one, many, or no triangles that have one angle measure of 60^(∘), one angle measure of 70^(∘), and a side length of 10 centimeters between the two angles. First, we can use a ruler to draw a 10-centimeter side of our triangle.

To find the position of the third vertex, we can begin by drawing an angle of 70^(∘) using a protractor. Let's call the vertex of this angle A.
Angle of 60 degrees

Now we can draw the 70^(∘) angle with its vertex at the other point of the 10-centimeter side of our triangle. We can call this vertex B.

Angle of 70 degrees

The third vertex of our triangle is the point of intersection between the two rays. We can denote the vertex with C. Finally, we can draw a triangle with the given measures.

triangle with angles 60, 70, and 10 cm side

We know that the sum of angle measures in a triangle is 180^(∘). This means that the third angle measure in our triangle is always the same. In this case, there is only one triangle that has the given description.