Final answer:
The length of the third side of a triangle, when the other two are 11 and 20, should be between 9 and 31, not inclusive. This is based on the triangle inequality theorem.
Step-by-step explanation:
The measure of the third side of a triangle, when the other two sides are given as 11 and 20, can be determined by using the triangle inequality theorem. This theorem states that the length of any side of a triangle must be less than the sum of the other two sides and more than the absolute difference of the other two sides.
Therefore, the third side must be less than 11 + 20 = 31 and more than |20 - 11| = 9. So, the third side must be between 9 and 31, not inclusive. This can be written as the inequality: 9 < x < 31.
Learn more about Triangle Inequality Theorem