Question

If each interior angel of a regular polygon is 135. Then number of diagonals of the polygon

Answer 1

see sum of interior angles of a polygon is given by (2n-4)×90 so
(2n-4)90=135n
finding n=8 it is regular octagon
no.of diagonals is given by
$\frac{n \times( n - 3)}{2}$

so putting n as 8 we get 20 as ans