Masculine and feminine noun?
If every adjective could be either masculine or feminine like cansado cansada enojado enojada
then what about feliz(happy), triste(sad) I don't know how to change those because those dont end in either 'a' or 'o'
Adjectives like feliz and triste are "neuter" and don't need to be changed according to gender. They are fine as they are. However, number is still important:
Mi mamá está feliz.
Mi papá está feliz.
Los dos están felices.
That's because these are invariable.
I'm not 100% positive (someone please correct me if I'm wrong), but I think for neuter adjectives you just leave them as they are. There is no change necessary because there is nothing to change.