## Precalculus (6th Edition) Blitzer

The trigonometric ratios apply to the right angle triangle and in the right angle triangle the largest side is the hypotenuse. So, the ratio of $\frac{\text{opposite}}{\text{hypotenuse}}\,\text{ and }\,\frac{\text{adjacent}}{\text{hypotenuse}}$ will be less than $1$ because the denominator has the hypotenuse (the largest side).