If the statement says it's so, then you have to adhere to that. Don't take away from it, and don't assume other unstated possibilities. Don't add to it, and don't disallow other unstated possibilities. Translate the statements in the original problem into equations in terms of your variables. Keep the quadratic formula close at hand.
Geometry is like owning a toolbox.
You need to have tools to solve problems. Geometry is like using a toolbox. You need to know what tools are in your box and how to use each one of them. Geometry is like using a toolbox effectively. You need to know what you're trying to accomplish, and you need to know which tools will get the job done.