I need help on 19 and 20. Please help me. Please don’t put a link. Please help me.

Answer:
19:
4 < third side < 14
20:
3 < third side < 13
Step-by-step explanation:
hint: go to http://www.17 28.org/trianinq.htm
(fix the space between 17 and 28)
you're welcome xx