The angles of an equilateral triangle are congruent. If x represents the measure of one angle of an equilateral triangle, which equation represents the sum of the angle measures of the triangle?

1. x + x = 90%

2. x + x + x = 90%

3. x + x = 180%

4. x + x + x = 180%

4) x + x + x = 180°

An equilateral triangle has three sides of equal length. Its interior angles are also equal. Since interior angles of a triangle should sum up to 180°, then each angle is 60°, making each angle congruent with one another.

So if x is equal to one angle and triangles have three angles then,

x + x + x = 180°

or 3x = 180°