For regular polygons all internal angles have the same The size of a single internal angle may be found using the formula: angle \( =\frac{\text { sum of all angles }}{\text { number of angles }} \) In an equilateral triangle, the number of sides \( n=3 \), \( 180^{\circ} \div 3= \) ? The size of the internal angles of an equilateral triangle must be

In an equilateral triangle, the number of sides \( n = 3 \). To find the size of a single internal angle, we can use the formula for the sum of the internal angles of a polygon, which is given by: \[ \text{Sum of internal angles} = (n - 2) \times 180^\circ \] For an equilateral triangle: \[ \text{Sum of internal angles} = (3 - 2) \times 180^\circ = 1 \times 180^\circ = 180^\circ \] Now, since all internal angles in an equilateral triangle are equal, we divide the sum of the internal angles by the number of angles (which is also the number of sides): \[ \text{Size of a single internal angle} = \frac{\text{Sum of internal angles}}{\text{Number of angles}} = \frac{180^\circ}{3} = 60^\circ \] Therefore, the size of the internal angles of an equilateral triangle must be \( 60^\circ \).