If x square is equal to x then what is the value of x

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¯¯¯¯¯¯¯¯)?

Which one ? is the answer and how to find this answer

Use δjkl and δmpn to determine whether don's claim is true or false. which of the following should don use to prove the triangles are similar? sss sas aas aa