For example: is congruent to: See Pythagoras' Theorem to find out more If the hypotenuse and one leg of one right-angled triangle are equal to the corresponding hypotenuse and leg of another right-angled triangle, the two triangles are congruent.
After trigonometry has been introduced, the cosine rule can be used to find the sizes of these angles. There is no SSA method. The following postulates and theorems are the most common methods for proving that triangles are congruent or equal.
These parts are equal because corresponding parts of congruent triangles are congruent. The third pair of congruent sides is the side that is shared by the two triangles. For example: See Solving ASA Triangles to find out more If two angles and the included side of one triangle are equal to the corresponding angles and side of another triangle, the triangles are congruent.
Many results of this type will be discussed in the module, Parallelograms and Rectangles.