1. the diagram shows ten equal discs that lie between two concentric circles- an inner circle and an outer circle. each disc touches two neighbouring discs and both circles. the inner circle has radius 1 what is the radius of the outer circle? 1 +sin 18â° c sin 36â° 2 9 a 2 tan 36â° d cos 18â° 1 sin 36â° 1 sin 18 5