How do Mendel’s experiments show that traits are inherited independently?

It was shown by a dihybrid cross. Here he used two traits, round seed (R)and wrinkled seed(r), and yellow(Y) and green(y) colored seed.

The round is dominant over wrinkled and yellow dominant over green. The F2 generation had a phenotype of 9:3:3:1. Where 9 were Round and Yellow seeds (RRYY), 3 were Round and green (RRyy), 3 were wrinkled and yellow (rrYY) and 1 was wrinkled and green (rryy). Thus this shows that the gametes segregate independently and are inherited accordingly