In order to determine the ratio of the hypotenuse to the short leg, use the sine of angle 30°:
sin 30° = opposite side / hypotenuse
Take intop account that sin30° is jsut the same the required ratio.
Moreover, consider that sin 30° = 1/2, which is the same that:
opposite side / hypotenuse = 1/2
or
hypotenuse / opposite