Question

Please help me with #7

Answer 1

Step-by-step answer:

This is a regular heptagon, means it has 7 congruent sides and 7 congruent vertex angles.

To work with polygons, there is a very important piece of information that you must know to solve the majority of related problems.

This is:

sum of exterior angles of polygons = 360 degrees.

If you don't remember the 360 degrees, think of the sum of exterior angles of an equilateral triangle, which is 3*(180-60)=3*120=360!  It works!

For a regular heptagon, c = 360/7=51.43 degrees approx.

This means that each vertex angle measures

vertex angle = 180-c

So since 2d+the vertex angle = 360, we have

2d+(180-c)=360

solve for d:

2d=360-(180-c)=180+c

d=(180+c)/2=90+c/2=115.71 degrees. (approx.)