Geometry: Polygons Flashcards
What is a convex polygon?
All the diagonals fit within the polygon
What is a concave polygon?
A polygon where at least one diagonal crosses the boundary (edge) of the polygon
The sum of all the interior angles of a polygon is….
180(#sides - 2)
The AVERAGE of all the interior angles of a polygon is….
180(#sides - 2) / #sides
The sum of all the EXTERIOR angles of a polygon is….
360
The AVERAGE of all the EXTERIOR angles of a polygon is….
360 / #sides
What is the sum of the interior angles of a quadrilateral?
360
What is the area of a rectangle?
length x width
What is the area of a parallelogram?
Length x height
height NOT shorter side
What is a trapezoid?
A quadrilateral where two opposing sides are parallel but the other two are not.
How do you find the area of a trapezoid?
(ParallelSide1 + ParallelSide2)(Height) / 2
What is a isosceles trapezoid?
One where the unparalleled sides are equal in length
What are four possibilities for rectangles with perimeter of 100?
1 x 49
15 x 35
20 x 30
25 x 25
What are five possibilities of rectangles with an AREA of 100?
1 x 100
2 x 50
4 x 25
5 x 20
10 x 10
How many sides does a polygon have if the average of its interior angles is 108?
180(x - 2)/x = 108
180x - 360 = 108x
72x = 360
x = 5
