The thing we have to do to determinate if the triangles are similar or not, it's prove that the sides of the bigest triangle are multiples of the smallest one.
You can do it easily by dividing each side:
First the smallest catetus:
Then the largest catetus:
Then the hypotenuse:
Thus, the bigest triangle sides are multiples of the smallest one. For this reason the triangles are similar to each other.