Carcass wrote:

Total internal angle: (n-2) x 180-degree

n- number of sides the polygon has.

Since parallelogram has four sides.

Attachment:

parallelogram (2).jpg

It has four sides.

2. Plugging it into the equation above, Sum of interior angle= (4–2) x 180

3. Sum of interior angle= 360°.

You may think of square and rectangle which have four sides, and yeah they have the same sum of the interior angle which is 360°.

Conclusion: any angle is 90°

Hope this helps.

Source

QuoraNo, for parallelogram, we cannot say that. It is not an regular polygon. The formula Total internal angle: (n-2) x 180-degree then Total internal angle: (n-2) x 180-degree/n works for regular polygon. Yes, it is a polygon with 4 sides but not a regular polygon . we can only say consecutive angles 180 and opposite angle are equal but we cannot take any decision about individual angle.

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Please let me know if I am wrong