There is a relationship between angles in a right triangle and the ratios of the sides. We call the relationships sine, cosine, and tangent. I taught Marcos the saying "Some Old Horse, Came a Hopping Through Our Alley". It is to help him remember sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite/adjacent. Marcos's assignment is p.648 (2-32 even).