1. **State the problem:** We need to determine which shortcut can be used to prove that the two triangles shown are similar. 2. **Given information:** The two triangles share a common angle at the bottom right vertex. 3. **Important observations:** - Both triangles have right angles (one at the top vertex of the smaller triangle and one at the bottom left vertex of the larger triangle). - They share a common angle. 4. **Recall similarity shortcuts:** - **AA (Angle-Angle):** Two angles of one triangle are congruent to two angles of another triangle. - **SSS (Side-Side-Side):** All three sides of one triangle are proportional to the three sides of another. - **SAS (Side-Angle-Side):** Two sides and the included angle of one triangle are proportional/congruent to those of another. - **AAS (Angle-Angle-Side):** Two angles and a non-included side are congruent/proportional. - **Hypotenuse-Leg (HL):** For right triangles, if the hypotenuse and one leg are congruent, triangles are congruent (not similarity). 5. **Apply to this problem:** - Since both triangles have right angles and share a common angle, they have two angles congruent. - By the AA similarity criterion, two triangles with two pairs of congruent angles are similar. 6. **Conclusion:** The similarity shortcut is **AA (Angle-Angle)**. **Final answer:** AA similarity shortcut can be used to prove the triangles are similar.