Question

A heptagon has three angles equal to 120°, and the other four angles are equal. Find all the angles.

Answer 1

The sum of the interior angles of heptagon
= (n - 2) x 180°
= (7 - 2) x 180°
= 5 x 180°
= 900°
Since, three angles are equal to 120°,
The sum of remaining four angles
= 900° - 3 x 120°
= 900° - 360°
= 540°
Since, these angles are equal,
The measure of each equal angle

= `(540°)/(4)`
= 135°
Thus, the angles of heptagon are 120°, 120°, 120°, 135°, 135°, 135°, 135°.