I WIL GIVE BRAINILIEST IF YOU GIVE EXPLANATION FOR BOTH please dont let me fail

How do the definitions, properties, and postulates you've learned about line segments, parallel lines, and angles to define the shapes of polygons

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Are the corresponding angles congruent? explain why or why not.