Question: Which statements about the angles of the triangle are true? Check all that apply.
a Angle 1 is an exterior angle.
b Angle 2 is an exterior angle.
c Angle 4 is an exterior angle.
d Angle 7 is an adjacent interior angle.
e Angle 6 is an adjacent interior angle. It is adjacent to the exterior angle 4.
f Angles 6 and 8 are remote interior angles to the exterior angle 1.
g Angles 6 and 7 are remote interior angles to the exterior angle 2.
h Angles 7 and 8 are remote interior angles to the exterior angle 4.
1. **Problem Statement:** Determine which statements about the angles of the given triangle and its exterior angles are true.
2. **Key Definitions:**
- An **exterior angle** of a triangle is an angle formed by one side of the triangle and the extension of an adjacent side.
- An **adjacent interior angle** is an interior angle next to an exterior angle, sharing a common side.
- **Remote interior angles** are the two interior angles of the triangle that are not adjacent to a given exterior angle.
3. **Analyze each statement:**
- a) Angle 1 is an exterior angle.
- Since Angle 1 is formed outside the triangle by extending a side, **this is true**.
- b) Angle 2 is an exterior angle.
- Angle 2 is inside the triangle, so **false**.
- c) Angle 4 is an exterior angle.
- Angle 4 is outside the triangle formed by extending a side, so **true**.
- d) Angle 7 is an adjacent interior angle.
- Adjacent interior angles are inside the triangle next to an exterior angle. Angle 7 is inside and adjacent to an exterior angle, so **true**.
- e) Angle 6 is an adjacent interior angle. It is adjacent to the exterior angle 4.
- Angle 6 is inside the triangle and shares a side with exterior angle 4, so **true**.
- f) Angles 6 and 8 are remote interior angles to the exterior angle 1.
- Exterior angle 1 is adjacent to one interior angle; the other two interior angles are remote. Angles 6 and 8 are inside but only one is remote to angle 1. Since angle 8 is not adjacent to angle 1, **true**.
- g) Angles 6 and 7 are remote interior angles to the exterior angle 2.
- Angle 2 is interior, so it cannot have remote interior angles. **False**.
- h) Angles 7 and 8 are remote interior angles to the exterior angle 4.
- Exterior angle 4 is adjacent to angle 6, so remote interior angles are the other two interior angles 7 and 8. **True**.
4. **Final answers:**
- True: a, c, d, e, f, h
- False: b, g