What does ntr stand for?

Who invented trigonometry? What makes charybdis better than scylla? What does treachorous mean? What is the range of y equals -sin x? What is the equation for Pythagoras therum? How big is trnidad? What does it mean to work like a Trojan? How long did the tri state tornado last for? What is the IMA formula of a wedge? What is the period of the sinusoid given by y equals -3 cos 2 pi over 5x? What did Saint Trifonas do? How high does the top guardrail have to be from the working surface on a scaffold? Why are there two sine cosine and tangent ratios? How long should you wait to change your tragus piercing? Define the function of range and domain? How many congruent angles does a dart have? Is trim a short vowel sound? Can the angle of incidence be greater than the angle of reflection when plane mirror? What are Icarus symbols? How are tragus earrings pierced?