Reasoning about angles in a triangle

1. Rotate triangle ABC 180° around the midpoint of side AC. Label the new vertex D.

2. Rotate triangle ABC 180° around the midpoint of side AB. Label the new vertex E.

3. Look at angles 3, 4, and 7. Without measuring, write what you think is the sum of the measures of these angles. Explain or show your reasoning.

Tags

CCSS.HSG.CO.A.4

Rotate triangle ABC 180° around the midpoint of side AB. Label the new vertex E.

1. Is the measure of angle 3 equal to the measure of any angle in triangle ABC? If so, which one? If not, how do you know? Use numbers to represent angles.

Tags

CCSS.8.G.A.3

CCSS.HSG.CO.A.5

1. Rotate triangle ABC 180° around the midpoint of side AC. Label the new vertex D.

2. Is the measure of angle 7 equal to the measure of any angle in triangle ABC? If so, which one? If not, how do you know? Use numbers to represent angles.

Tags

CCSS.8.G.A.3

Is it always true that the sum of the angles in a triangle is 180°?

Tags

CCSS.8.G.A.5

Find the measure of the missing angle in the Figure shown

Tags

CCSS.8.G.A.5

Find the measure of the missing angle in Figure 2

Tags

CCSS.8.G.A.5

Find the measure of the missing angle in Figure 3

Tags

CCSS.8.G.A.5

Find the measure of the missing angle in Figure 4

Tags

CCSS.8.G.A.5

Here is a diagram of triangle DEF. Find the measures of angles q, r, and s.

Tags

CCSS.8.G.A.5

Here is a diagram of triangle DEF. Find the sum of the measures of angles q, r, and s.

Tags

CCSS.8.G.A.5