Is getting help from your mom or any other relatives possible? You had the right idea by getting help from your brother since you said your dad respects your brother. That is the key in my opinion. Find and seek out people your dad will listen to and then team up on him and wear him down. Lying is an option but probably a last resort. It is better, I think, to gather information about career options with an econ degree and then steadfastly stick to your guns (so to speak).
Ultimately, your dad wants you to be happy and successful and it seems to me Islamic women and entering the workforce WW so it might be time to educate your dad about that. But there has to be friends of your dad, or your mom, or someone besides your brother who can help you. You might also indicate to your dad what will happen if you can’t major in what you want … go on strike :-). He will cave in.