Question

wue ut x.
rior angles.
12. Two angles of a polygon are right angles and every other angle is 120°. Find the number
of sides of the polygon.
[Hint. Let the number of sides be n, then 2 x 90° + (n - 2) x 120° = (12-2) x 180°)
The sum of interior angle​

Answer 1

Answer:

Two angles of a polygon are right angles and the remaining are 120° each.

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asked May 27, 2019 in Class VIII Maths by muskan15 (-3,443 points)

Two angles of a polygon are right angles and the remaining are 120° each. Find the number of sides in it.

understanding shapes (including polygons)

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answered May 27, 2019 by navnit40 (-4,939 points)

Let number of sides = n

Sum of interior angles = (n – 2) × 180°

= 180n – 360°

Sum of 2 right angles = 2 × 90°

= 180°

∴ Sum of other angles = 180n – 360° – 180°

= 180n – 540

No. of vertices at which these angles are formed = n – 2

∴ Each interior angle = (180n – 540)/(n – 2)

∴ (180n – 540)/(n – 2) = 120°

180n – 540 = 120n - 240

180n – 120n = -240 + 540

60n = 300

n = 300/60

n = 5