##\sin 60° = \frac{opposite}{hypotenuse} = \frac{y}{r}##

##\sin 30° = \frac{opposite}{hypotenuse} = \frac{x}{r}##

The questions are:

1. What is the opposite and hypotenuse of sin 90°?

2. I am guessing that the opposite and hypotenuse of sin 90 is

r and y respectively so that ##\sin 90° = \frac{opposite}{hypotenuse} = \frac{r}{y}##.

Why sin 90° = 1?