Someone help me asap

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 graph represents the function f(x)=4[x]?

An angle bisector ac divides a trapezoid abcd into two similar triangles ? abc and ? acd. find the perimeter of this trapezoid if the leg ab=9 cm and the leg cd=12 cm.