From the diagram, ΔRST, ΔRUS and ΔSUT are right triangles. This means that the corresponding legs of the three triangles are proportional, then we can say that the triangles are similar by side-angle-side similarity. RS/RU=RU/SU In the figure we can also notice that the acute angles of the corresponding angles are similar, then by angle-angle similarity the triangles are similar. ∠TRS~∠URS~TSU This implies that: ΔSUT~ΔSRU~ΔRTS
