You can
put this solution on YOUR website!Whoops, originally thought the sides were 1:2:3, not the angles.
If the angles are in the ratio 1:2:3, the triangle is a 30-60-90 triangle (by using x + 2x + 3x = 180 --> x = 30). The shortest side has length

so the next larger side is the shortest side times

(since the next larger side cannot be the hypotenuse). So the next larger side is 15.