1 Answer

Speciousfool · Answer 1 · 2023-01-18T03:58:38+0000

To be able to determine the sum of all angles in a 21-gon or a polygon with 21 sides will be using the following formula:

$(n\text{ - 2) x 180}$

Where,

n = number of sides

We get,

$(n\text{ - 2) x 180}$
$\text{ (21 - 2) x 180}$
$\text{ 19 x 180}$
$\text{ 3,420}^(\circ)$

Therefore, the sum of all angles in a 21 - gon is 3,420°.

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