The sum of the interior angles of a heptagon is?

A.) 900°

B.) 1,080°

C.) 1,260°

D.) 1,440°

I got A, but not for sure.

Question

The sum of the interior angles of a heptagon is?

A.) 900°

B.) 1,080°

C.) 1,260°

D.) 1,440° 

I got A, but not for sure.

mathstudent55 · Answer

How many sides does a heptagon have?

anonymous · Answer

7?

mathstudent55 · Answer

triangle = 3 sides
quadrilateral = 4 sides
pentagon = 5 sides
hexagon = 6 sides
heptagon = 7 sides
octagon = 9 sides
nonagon = 9 sides
decagon = 10 sides

mathstudent55 · Answer

Correct.

mathstudent55 · Answer

Now just use the same formula you have used in the last two problems.

Here it is again:

$S = (n - 2)180$

where S = sum of the measures of the interior angles, and n = number of sides.

mathstudent55 · Answer

Rewrite the formula exactly as it is.
The more you write it, the faster you'll memorize it.
Then rewrite it with 7 instead of n.

$S = (n - 2)180$

$S = (7 - 2)180$

Now do 7 - 2.
What is 7 - 2 = ?

anonymous · Answer

5

mathstudent55 · Answer

Great.
Now you write:

$S = 5(180) $

Finally, what is 5 * 180 = ?

anonymous · Answer

900

anonymous · Answer

Thank you!

mathstudent55 · Answer

Correct.
This is what your notebook should look like:

$S = (n - 2)180$

$S = (7 - 2)180$

$S = 5(180) $

$S = 900$

The sum of the measures of the interior angles of a heptagon is 900 degrees.

mathstudent55 · Answer

If you always start with the formula you will have to advantages:
1. you will get the formula right
2. you will memorize the formula from writing it many times

mathstudent55 · Answer

You're welcome.