HELP ASAP ALGEBRA 2 QUESTION GIVING 15 POINTS PLUS BRAINLEST

How can we find the measure of an exterior angle if we know the measurement of an interior angle

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¯¯¯¯¯¯¯¯)?

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi