Any angle that you like.
An interior angle of a convex heptagon can have any value in the range (0, 180) degrees.
128.571428 repeating
Each interior angle is approximately 128.57 * * * * * That is only true of a REGULAR heptagon. The question does not state that it is regular.
It is 128.57 degrees (approx). 900/7 degrees, exactly.
The 7 interior angles of a heptagon add up to 900 degrees
An interior angle of a convex heptagon can have any value in the range (0, 180) degrees.
An interior angle of a heptagon can have any value in the range (0, 360) degrees - other than 180 degrees.
A heptagon has 7 sides and 7 angles. The sum of the interior angles is 900°. If the heptagon is a regular heptagon, meaning all sides and angles are congruent, then the formula (180(n-2))/ n gives the individual interior angle measure. "n" is the number of sides in this case. In a regular heptagon, the interior angle measures 128 4/7 degrees.
128.571428 repeating
A heptagon. It can have a reflex interior angle, a triangle cannot.
Each interior angle is approximately 128.57 * * * * * That is only true of a REGULAR heptagon. The question does not state that it is regular.
An interior angle of a heptagon can have ANY value between 0 and 360 degrees.
The 7 exterior angles of an heptagon add up to 360 degrees The 7 interior angles of an heptagon add up to 900 degrees
the interior angle is about 128.571428 the exterior angle is about 51.4285
900 degrees
heptagon
There is no such thing as a hectogon. A heptagon has 7 vertices. Each exterior angle of a regular heptagon is 360/7 degrees. So each interior angle is 180 - 360/7 = 128.57 degrees (approx).