How do you find the hypotenuse of a 30-60-90 triangle?

Can't gugys answer the ratio question. this is urgent the plans of a building is drawn toward scale of 1: 1000. kfc the foyer on the plans measures 62mm by 54mm, how large is the foyer in real life?

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?

How to do this , and can some one explain