A shape with three or more sides is known as a polygon - triangles, hexagons, quadrilaterals, octagons and more are polygons. When asked for the sum of the interior of a polygon there are a couple ways to solve the problem. Knowing each of these and when to use which one is important for getting a high score on the SAT math section. 

 

TIP: When stuck trying to find the length of a side it is not necessary to do the math all of the time. When able to eliminate two or more wrong answers there are ways to be able to quickly get the correct answer by using the edge of the answer sheet as a ruler to measure the length.