⁦Symmetry of polygons, interior and exterior angles⁩

⁦This studio follows the Iranian Grade 8 lessons on polygons and symmetry, interior angles and exterior angles⁩. A مضلع ⁦is a closed broken line whose sides meet only at the corners⁩. ⁦If all sides and all angles are equal, it is a⁩ مضلع منتظم.

⁦A regular polygon has⁩ محور تناظرs: ⁦a triangle 3, a square 4, a pentagon 5, and so on⁩. ⁦A regular n-gon has n lines of symmetry⁩.

The زاوية داخلية⁦s of an n-sided polygon add up to (n − ٢)×١٨٠ degrees⁩. ⁦In a regular polygon all angles are equal, so each angle is that total divided by n⁩.

⁦If you extend one side beyond a corner, the angle between the extension and the next side is the⁩ زاوية خارجية. ⁦The interior and exterior angle at a corner lie side by side on a straight line⁩: ⁦they add up to 180 degrees⁩.

⁦The exterior angles of any convex polygon (one at each corner) always add up to 360 degrees⁩: n×١٨٠ − (n − ٢)×١٨٠ = ٣٦٠.