An equilateral triangle has 3 interior angles each measuring 60 degrees
Hint: in a regular polygon interior plus exterior = 180o, always.
It is a regular 20 sided polygon
If exterior angles are 120 then interior angles must be 60 so you have an equilateral triangle
There is no regular polygon with an interior angle of 20o. If the interior angle is 120o then there are six sides and the sum of the angles is 720o.
Each interior angle measures 108 degrees and the 5 angles of the regular pentagon add up to 540 degrees
If it's a regular polygon then each interior angle measures 120 degrees.
A four-sided regular polygon (square or rectangle) has 900 interior angles.
360
cheat!
The interior angle of any regular polygon can be calculated using the formula 180 * (n - 2) / n, where n is the number of sides. In this case, since each exterior angle measures 72 degrees, the interior angle would be 180 - 72 = 108 degrees. So the measures of the interior angles in this regular polygon would be 108 degrees.
The polygon will have 12 equal sides and each interior angle measures 150 degrees.
There are 5 interior angles and each one measures 108 degrees (180-72). Since the sum of exterior angles of any polygon is 360⁰, then that polygon would have 5 angles (360/72). So the sum of interior angle measures is 540⁰.