Examine the triangles, which are similar. Two similar triangles. The first triangle has a side length of 12 meters, which corresponds to the second triangle's side of 3 meters. The missing side of the first triangle corresponds to a side of 5 meters on the second triangle. © 2017 StrongMind. Created using GeoGebra. How many meters long is the missing side? Note: The triangles may not be drawn to scale. Enter your answer as a number, like this: 42