Isn't it a^2 = b^2 + c^2?.
Do I take h to be hypotenuse, o = opposite and a = adjacent? Reminds me of the silly little acronym we learned in middle school: SOHCAHTOA. It doesn't stand for anything and we just pronounced it 'SO-KA-TOE-UH'. Yet I remember it to this day and it is an easy way to remember sine=opposite over hypotenuse, etc.