A rule of Polygons is that the sum of the exterior angles must equal 360. Remember that for your testing. A polygon is where all sides equal the same amount, in your case, 18 degrees. So divide 360 by 16, equalling D.20 Good Luck!
draw a point for the center draw lines from the center to each vertex you get lots of triangles
see the diagram so it won't be confusing an since I will be refering to stuff in there
striahge line=180 so 18+x+x=180 minus 18 2x=162 divide 2 x=81 now we know 2 interior angles x and y=81 angles ina triangle add to 180 therefor x+y+z=180 81+81+z=180 162+z=180 minus 162 z=18
all central angles add up to 360 how man y are there? 18 times how many=360 divide both sidess by 18 how many angles=20 20 central angles=20 sides
4.
we can compare using side to angle ratios since 9=9 and they share a side, the sides PQ and SR and congruent and PS is congruent to PS therfor the only different side is QS and PR
