Sum of the measures of the interior angles of a heptagon

[yormmanz]

PLEASE HELP1.What is the sum of the measures of the interior angles of a heptagon?

A. 1260∘
B. 2520∘
C. 900∘
D. 1800∘

my answer is C

5.If the sum of the interior angle measures of a polygon is 3600∘, how many sides does the polygon have?
A. 22 sides
B. 20 sides
C. 18 sides
D. 10 sides

MY ANSWER ?

3.What is the angle measure of each exterior angle of a regular octagon?
A. 45∘
B. 135∘
C. 360∘
D. 1080∘

MY ANSWER ?

 

[skeeter]

couple of pieces of information to assist you ...

the sum of the interior angles of a convex n-gon is $(n-2)180^\circ$

the sum of the exterior angles of a convex n-gon is $360^\circ$