The document provides instructions for an activity to measure angles of triangles and compare exterior angles to interior angles. Students are asked to measure and record the angles of three triangles, then compare each exterior angle to the remote interior angles using relation symbols. All comparisons showed the exterior angle is greater than the remote interior angle, allowing students to state the exterior angle inequality theorem.

1. ACTIVITY 6 (answer key)
MEASURE MANIA: EXTERIOR OR REMOTE INTERIOR?
Materials Needed: Protractor, Manila Paper, and Ruler.
Procedures:
1. Measure the numbered angles of ∆HEY, ∆DAY, and ∆JOY.
2. Replicate the table in this activity on a piece of manila paper.
3. Indicate the measures on your table and write your answers to
the questions on a piece of manila paper.
1. Compare the measure of exterior ∠1 with either remote interior ∠4 or
∠6 using the relation symbols >, <, or =.
• In ∆HEY, m∠1 is > m∠4.
• In ∆HEY, m∠1 is > m∠6.
• In ∆DAY, m∠1 is = m∠4.
• In ∆DAY, m∠1 is > m∠6.
• In ∆JOY, m∠1 is > m∠4.
• In ∆JOY, m∠1 is > m∠6.

2. 2. Compare the measure of exterior ∠2 with either remote interior ∠5 or
∠6 using the relation symbols >, <, or =.
• In ∆HEY, m∠2 is > m∠5.
• In ∆HEY, m∠2 is > m∠6.
• In ∆DAY, m∠2 is > m∠5.
• In ∆DAY, m∠2 is > m∠6.
• In ∆JOY, m∠2 is < m∠5.
• In ∆JOY, m∠2 is > m∠6.
3. Compare the measure of exterior ∠3 with either remote interior ∠4 or
∠5 using the relation symbols >, <, or =.
• In ∆HEY, m∠3 is > m∠4.
• In ∆HEY, m∠3 is > m∠5.
• In ∆DAY, m∠3 is > m∠4.
• In ∆DAY, m∠3 is > m∠5.
• In ∆JOY, m∠3 is > m∠4.
• In ∆JOY, m∠3 is > m∠5.

3. 4. Making? Conjecture: Your comparison between the measure of an exterior angle of a
triangle and either interior angle in this activity describes the Exterior Angle Inequality
Theorem. With the pattern that you observed, state the exterior angle inequality
theorem.
• The measure of an exterior angle of a triangle is triangle is greater than either of the
non-adjacent interior angles.