How do you find the sum of the measures of the interior angles of a 21-gon?

1 Answer
Shwetank Mauria
May 29, 2017

Sum of the measures of the interior angles of a #21# sided polygon is #3420^@#

Explanation:

Sum of the measures of the interior angles of a polygon of #n# sides is #(n-2)xx180^@#.

For example for a triangle, it is #(3-2)xx180^@=180^@#

and for a rectangle, it is #(4-2)xx180^@=2xx180^@=360^@#

Hence sum of the measures of the interior angles of a #21# sided polygon is #(21-2)xx180^@=19xx180^@=3420^@#

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