Which number best represents the slope of the graphed line?

(98 points) i need with 5 questions. answer definitions are welcomed, but not necessary.

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¯¯¯¯¯¯¯¯)?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?