After an angle is intercepted by a polymorph, the sum of the inner angles of the polymorph is 1260 degrees. How many sides is the original polygon,

After an angle is intercepted by a polymorph, the sum of the inner angles of the polymorph is 1260 degrees. How many sides is the original polygon,

Let the number of sides of the polygon be n '
That is, (n ′ - 2) &; 180 ° = 1260 °, then n ′ = 9
Therefore, according to the situation of cutting, there are some problems
1. On the two adjacent sides, n = n-1 = 8;
2. Cut on one corner and one side: n = n = 9;
3. Tangent on two corners: n = n + 1 = 10