Sum of interior angles of a polygon of (n+1) sides =
The correct option is A (n−1)×180∘
We know that
Sum of interior angles of a polygon of (n) sides =(n−2)×180∘
∴ Sum of interior angles of a polygon of (n+1) sides
=(n+1−2)×180∘ [Substituting n=n+1]
=(n−1)×180∘