Both are correct but the meaning is slightly different. The first one means in general, the teacher will be angry with you IF you forget to do your homework, that is the action has not been completed yet. The "had forgotten" is the past participle case which means that the action is completed.

neither, really.. if you say 'because', both are correct. Actually, she got angry WHEN you told her you forgot/had forgotten... See? :)

The second is correct. In order to make #1 correct, you say "1- My teacher "GETS" angry with me when I forget to do my homework." hope this helps :)

In this case, 2 is more correct. "My teacher got angry with me when I had forgotten to do my homework." You can also say "My teacher got angry with me when I forgot to do my homework." For the first one, you would say "My teacher gets angry with me when I forget to do my homework."

or simply "My teacher got angry with me when I forgot to do my homework" (but I realise this wasn't one of the options!)