The sum of interior angles of an equilateral triangle, a regular quadrilateral, a regular pentagon.....etc written as a sequence is
180∘,360∘,540∘⋯⋯
The sum of interior angles of a n-sided regular polygon is given by (n−2)×180∘.
Hence sum of interior angles of an equilateral triangle is 180∘, a regular quadrilateral is 360∘ and that of a regular pentagon is 540∘.
Hence the corresponding sequence is given by:
180∘,360∘,540∘⋯⋯