Trigonometric ratios of an acute angle

In a right triangle choose one acute angle θ. The side opposite the right angle is the hypotenuse. The side facing θ is the opposite side, and the other leg, touching θ, is the adjacent side. Three ratios of these sides have names: sin θ = opposite ÷ hypotenuse, cos θ = adjacent ÷ hypotenuse and tan θ = opposite ÷ adjacent. If you look from the other acute angle, “opposite” and “adjacent” swap. These ratios are numbers without units, and they depend only on the angle, not on the size of the triangle: a bigger triangle with the same angle is similar, so its sides are in the same ratios. Since the hypotenuse is the longest side, sin θ and cos θ are always smaller than 1, but tan θ can be bigger than 1. Note that sin θ is one number, not sin × θ.