Can someone help me out with this question? The question is about circle diameters. I'm unfamiliar with finding the length of the arc. If someone answers can you explain the answers step by step, thank you!

20 pointstwo right triangles are graphed on a coordinate plane. one triangle has a vertical side of 3 and a horizontal side of 7. the other triangle has a vertical side of 9 and a horizontal side of 21. could the hypotenuses of these two triangles lie along the same line? yes, because they are both right triangles yes, because they are similar triangles no, because they are not similar triangles no, because one is larger than the other