In a museum there is a round window decorated with circular rings of the same size as in the diagram. The radius of the window is 45cm. Calculate the area that is not covered by the decoration. (Use pi=3.142)

Complementary angles: angles whose sum is 90 degrees.supplementary angles: angles whose sum is 180 degrees.straight angle: an angle that is worth 180 degrees. (can be a straight  line)right angle: an angle that is worth 90 degrees ( usually marked by a small box and is the angle in a rectangle and square)