Calculate Interior Angles: Finding Angle Measures in an Equilateral Triangle

To solve this problem, we'll follow these steps:

• Step 1: Identify that an equilateral triangle has all sides of equal length, which implies its angles are also equal.
• Step 2: Utilize the property that the sum of angles in any triangle is $180^\circ$.
• Step 3: Since each angle is equal in an equilateral triangle, divide the total sum of $180^\circ$ by 3.

Now, let's work through each step:
Step 1: In an equilateral triangle, all angles are equal in size.
Step 2: The sum of angles in any triangle is always $180^\circ$.
Step 3: Divide $180^\circ$ by 3.

Calculating $180^\circ \div 3 = 60^\circ$.

Therefore, the size of each angle in an equilateral triangle is $60^\circ$.