Lesson 15: Adding the Angles in a Triangle | Unit 1: Rigid Transformations and Congruence

Multiple Choice

In triangle $$ABC$$ , the measure of angle $$A$$ is $$40^\circ$$ . What are the possible measures for angles $$B$$ and $$C$$ if triangle $$ABC$$ is isosceles?

• (60 degrees, 80 degrees)
• (30 degrees, 110 degrees)
• (70 degrees, 70 degrees) or (40 degrees, 100 degrees)
• (50 degrees, 90 degrees)

Multiple Choice

In triangle $$ABC$$ , the measure of angle $$A$$ is $$40^\circ$$ . Give possible measures for angles $$B$$ and $$C$$ if triangle $$ABC$$ is right.

• Angle B can be 60 degrees and angle C can be 0 degrees.
• Angle B can be 30 degrees and angle C can be 10 degrees.
• Angle B can be 50 degrees and angle C can be 0 degrees, or any combination where B + C = 50 degrees.
• Angle B can be 70 degrees and angle C can be 20 degrees.

Multiple Choice

Is there is a triangle whose angles have these measures in degrees: 60, 60, 60

• Yes

• No

Multiple Choice

Is there is a triangle whose angles have these measures in degrees: 90, 90, 45

• Yes

• No

Multiple Choice

Is there is a triangle whose angles have these measures in degrees: 30, 40, 50

• Yes

• No

Multiple Choice

Is there is a triangle whose angles have these measures in degrees: 90, 45, 45

• Yes

• No

Multiple Choice

Is there is a triangle whose angles have these measures in degrees: 120, 30, 30

• Yes

• No

Draw

If you get stuck, consider making a line segment. Then use a protractor to measure angles with the first two angle measures.

Open Ended

Angle $$A$$ in triangle $$ABC$$ is obtuse. Can angle $$B$$ or angle $$C$$ be obtuse? Explain your reasoning.

Draw

On the grid, draw a scaled copy of quadrilateral $$ABCD$$ using a scale factor of $$\frac12$$ . A quadrilateral on a grid. Point A is 2 units right and 6 units up. Point B is 4 units right and 8 units up. Point C is 8 units right and 6 units up. Point D is 4 units right and 2 units up.