<Table> <Tr> <Th_colspan="2"> Regular icosagon </Th> </Tr> <Tr> <Td_colspan="2"> A regular icosagon </Td> </Tr> <Tr> <Th> Type </Th> <Td> Regular polygon </Td> </Tr> <Tr> <Th> Edges and vertices </Th> <Td> 20 </Td> </Tr> <Tr> <Th> Schläfli symbol </Th> <Td> (20), t (10), tt (5) </Td> </Tr> <Tr> <Th> Coxeter diagram </Th> <Td> </Td> </Tr> <Tr> <Th> Symmetry group </Th> <Td> Dihedral (D), order 2 × 20 </Td> </Tr> <Tr> <Th> Internal angle (degrees) </Th> <Td> 162 ° </Td> </Tr> <Tr> <Th> Dual polygon </Th> <Td> Self </Td> </Tr> <Tr> <Th> Properties </Th> <Td> Convex, cyclic, equilateral, isogonal, isotoxal </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Regular icosagon </Th> </Tr>

What is the interior angle of a 20 sided polygon