Adding the Angles in a Triangle: IM 8.1.15
[url=https://im.kendallhunt.com/MS/teachers/3/1/15/preparation.html]“Adding the Angles in a Triangle”[/url] from IM Grade 8 by [url=https://www.geogebra.org/m/gus8ffvr]Open Up Resources[/url] and Illustrative Mathematics. Licensed under the [url=https://creativecommons.org/licenses/by/4.0/]Creative Commons Attribution 4.0 license[/url].
Table of Contents
- Lesson 8.1.15
- IM 8.1.15 Lesson: Adding the Angles in a Triangle
- Practice 8.1.15
- IM 8.1.15 Practice: Adding the Angles in a Triangle
IM 8.1.15 Lesson: Adding the Angles in a Triangle
Complete the table by drawing a triangle in each cell that has the properties listed for its column and row. If you think you cannot draw a triangle with those properties, write “impossible” in the cell.
Share your drawings with a partner. Discuss your thinking. If you disagree, work to reach an agreement.
Your teacher will give you a card with a picture of a triangle. The measurement of one of the angles is labeled. Mentally estimate the measures of the other two angles.
[list=1][*]The measurement of one of the angles is labeled. Mentally estimate the measures of the other two angles.[br][/*][*]Find two other students with triangles congruent to yours but with a different angle labeled. Confirm that the triangles are congruent, that each card has a different angle labeled, and that the angle measures make sense.[br][/*][*]Enter the three angle measures for your triangle on the table your teacher has posted.[color=#ff0000][br][/color][/*][/list][br]You can use the applet below to store your information.
You are given three angles in the applet below. Can you make a triangle from each set that has these same three angles?
Here is a quadrilateral. Its tears are marked with different colors and those are lined up below.
What do you notice?
Move the angles to get different quadrilaterals. Do you have a conjecture about the angles?
IM 8.1.15 Practice: Adding the Angles in a Triangle
[size=150]In triangle [math]ABC[/math], the measure of angle [math]A[/math] is [math]40°[/math].[/size][br][br]Give possible measures for angles [math]B[/math] and [math]C[/math] if triangle [math]ABC[/math] is isosceles.
Give possible measures for angles [math]B[/math] and [math]C[/math] if triangle [math]ABC[/math] is right.
For the following sets of angles, decide if there is a triangle whose angles have these measures in degrees. If you get stuck, consider making a line segment. Then use a protractor to measure angles with the first two angle measures.
60, 60, 60
90, 90, 45
30, 40, 50
90, 45, 45
120, 30, 30
Angle [math]A[/math] in triangle [math]ABC[/math] is obtuse. Can angle [math]B[/math] or angle [math]C[/math] be obtuse?
Explain your reasoning.
Describe the transformation that could be applied to Polygon A to get Polygon B.
Describe the transformation performed above.
Describe the transformation that could be applied to Polygon A to get Polygon B.
Describe the transformation performed above.
Describe the transformation that could be applied to Polygon A to get Polygon B.
Describe the transformation performed above.