HOW CAN YOU DETERMINE IF TWO LINES ARE PERPENDICULAR?

First, do not use all caps, since this is like SHOUTING on the Internet. It is rude and will not get you faster or better service.

Second, your question was answered in your previous post.

Third, repeating your same question on multiple posts will not get you better or faster help. It just wastes our time looking at these repeated posts, when we could be answering other posts.

It might help if you realize that we are not always available. Volunteers search the message boards at least daily, if not more often. However, it might be a while before someone with expertise in your area reads your post(s). Typically your post will be answered within 24 hours.

I hope this helps you to understand the message boards better.