2D Shapes - Acute, Obtuse, and Right Angles Activity Worksheet

Problem Description:

The task is to identify and label the types of angles (acute, obtuse, or right) in each of the given 2D shapes. The instructions specify using the following codes:
- a for acute angles
- o for obtuse angles
- r for right angles

Solution Approach:

1. Understand the Definitions:
- Acute Angle: An angle less than 90°.
- Right Angle: An angle exactly 90°.
- Obtuse Angle: An angle greater than 90° but less than 180°.

2. Analyze Each Shape:
For each shape, examine its angles and classify them based on the definitions above.

3. Label the Angles:
Use the provided codes (`a`, `o`, `r`) to mark the angles in each shape.

---

Step-by-Step Analysis of Each Shape:

#### Shape 1: Square
- A square has four equal sides and four equal angles.
- Each angle in a square is 90°.
- Classification: All angles are right angles.
- Labels: `r r r r`

#### Shape 2: Right Triangle
- A right triangle has one angle that is 90° (right angle) and two other angles that are acute (less than 90°).
- Classification: One right angle and two acute angles.
- Labels: `r a a`

#### Shape 3: Equilateral Triangle
- An equilateral triangle has three equal sides and three equal angles.
- Each angle in an equilateral triangle is 60°.
- Classification: All angles are acute.
- Labels: `a a a`

#### Shape 4: Rhombus
- A rhombus has four equal sides, but its angles can vary.
- Opposite angles are equal, and adjacent angles are supplementary (sum to 180°).
- In this specific rhombus, two angles appear to be obtuse (> 90°), and the other two appear to be acute (< 90°).
- Classification: Two obtuse angles and two acute angles.
- Labels: `o o a a`

#### Shape 5: Diamond (Rhombus)
- Similar to Shape 4, this is also a rhombus.
- The angles appear to be the same as in Shape 4: two obtuse and two acute.
- Classification: Two obtuse angles and two acute angles.
- Labels: `o o a a`

#### Shape 6: Trapezoid
- A trapezoid has one pair of parallel sides.
- In this specific trapezoid, there are two right angles (90°), one acute angle, and one obtuse angle.
- Classification: Two right angles, one acute angle, and one obtuse angle.
- Labels: `r r a o`

---

Final Answer:

Here are the labels for each shape:

1. Square: `r r r r`
2. Right Triangle: `r a a`
3. Equilateral Triangle: `a a a`
4. Rhombus: `o o a a`
5. Diamond (Rhombus): `o o a a`
6. Trapezoid: `r r a o`

Boxed Answer:
\[
\boxed{
\begin{aligned}
1. & \quad r \, r \, r \, r \\
2. & \quad r \, a \, a \\
3. & \quad a \, a \, a \\
4. & \quad o \, o \, a \, a \\
5. & \quad o \, o \, a \, a \\
6. & \quad r \, r \, a \, o
\end{aligned}
}
\]