Lesson 15
Adding the Angles in a Triangle
Let’s explore angles in triangles.
Problem 1
In triangle \(ABC\), the measure of angle \(A\) is \(40^\circ\).
- Give possible measures for angles \(B\) and \(C\) if triangle \(ABC\) is isosceles.
- Give possible measures for angles \(B\) and \(C\) if triangle \(ABC\) is right.
Problem 2
For each set of angles, decide if there is a triangle whose angles have these measures in degrees:
- 60, 60, 60
- 90, 90, 45
- 30, 40, 50
- 90, 45, 45
- 120, 30, 30
If you get stuck, consider making a line segment. Then use a protractor to measure angles with the first two angle measures.
Problem 3
Angle \(A\) in triangle \(ABC\) is obtuse. Can angle \(B\) or angle \(C\) be obtuse? Explain your reasoning.
Problem 4
For each pair of polygons, describe the transformation that could be applied to Polygon A to get Polygon B.
Problem 5
On the grid, draw a scaled copy of quadrilateral \(ABCD\) using a scale factor of \(\frac12\).
![A quadrilateral on a grid.](https://staging-cms-im.s3.amazonaws.com/zAJDbs9KucK5TbTDFyf9tA26?response-content-disposition=inline%3B%20filename%3D%228-8.1.PP.7Grev1.png%22%3B%20filename%2A%3DUTF-8%27%278-8.1.PP.7Grev1.png&response-content-type=image%2Fpng&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAXQCCIHWF37H2AMFB%2F20240722%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20240722T155939Z&X-Amz-Expires=604800&X-Amz-SignedHeaders=host&X-Amz-Signature=e9b8d220e5861eb614dda5fe18108d3d694e35ad77fe917b005409afbe2e6c1c)