Trigonometry (10th Edition)

A parenthesis $“(“$ or $“)”$ is used to show exclusiveness. A square bracket $“[“$ or $“]”$ is used to show inclusiveness.
When graphing the solution set of a linear inequality, a parenthesis $“(“$ or $“)”$ is used to show that a number is exclusive and not part of the solution while a square bracket $“[“$ or $“]”$ is used to show that a number is inclusive and part of the solution.