you say, "There's a magic word. It's called the tangent of an angle," and leave him alone. He'll figure it out.
απαντάς: «Υπάρχει μια μαγική λέξη. Ονομάζεται η εφαπτόμενη μιας γωνίας» και τον αφήσεις μόνο του.