Answer: 1.12 B. sin(s) = cos(u) 1.13 C. showing similar trianglesStep-by-step explanation:1.12 First of all, it is useful to identify the complementary angles. These are the two acute angles in the same right triangle: (s, u) or (t, v), or the adjacent angles that together make a right ange: (s, t) or (u, v).Only choices B and D involve complementary angles. Only choice B shows the right relationship between trig functions of those angles.___1.13 It helps if you've seen the short, cute proof of the Pythagorean theorem using similar triangles. One of the early steps in the proof is to show the triangles are similar: choice C.Even if you've never seen that proof, you can still make a good guess as to the correct choice. Choices A and D are just plain incorrect. Choice B might be the end result of the proof of the Pythagorean theorem, but won't be a step in that proof. In any event, the point of the proof is to show AC^2 + BC^2 = AB^2, not the equation of choice B.That leaves choice C, which is both correct and likely to be a step in the proof.