A classroom display shows three regular polygons side by side: a regular decagon (10 sides), a regular heptagon (7 sides) and a regular 18-sided polygon. Use the display to answer the parts below.
(a)Work out the interior angle of the regular decagon.(2)
(b)Work out the interior angle of the regular heptagon (7 sides). Give your answer to 1 decimal place.(3)
(c)The class teacher asks the students to find the difference between the interior angles of the 18-sided polygon and the heptagon. Find this difference and give the answer to 1 decimal place.(5)
(Total for Question 10 is 10 marks)