Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The hinge theorem in geometry states that if two sides of one triangle are congruent to two sides of another triangle, and the included angle of the first is larger than the included angle of the second, then the third side of the first triangle is longer than the third side of the second triangle. The converse of the hinge theorem would be: If the two sides of one triangle are congruent to two sides of another triangle, and the third side of the first triangle is greater than the third side of the second triangle, then the included angle of the first triangle is larger than the included angle of the second triangle. In some textbooks, the theorem and its converse is written as the SAS Inequality Theorem and the SSS Inequality Theorem respectively.