Polygonal Angles 2 – 10-gon Angles

Geometry Level 2

What is the sum of the interior angles in a regular 10-gon?


The answer is 1440.

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14 solutions

Fardausur Rahaman
Jun 11, 2014

if join all angel with center then 10 triangle will create. Sum of 10 triangle's angles is 180*10=1800, avoid 360 of center then we get 1800-360=1440.

I didn't do that in that way but it's good process.....

Javers Argho Sarder - 6 years, 11 months ago

I think u can use this formula for any one...

n(180-360/n)

Javers Argho Sarder - 6 years, 11 months ago
Sateesh Natarajan
Jun 13, 2014

when sum of internal angle is asked for any of the regular polygon we can use the formula which is as under, 180 X (n-2)............where n is the number of sides of a polygon, hence, 180 X (10-2)=180 X 8 = 1440

Ahmad Bashir
Jun 7, 2014

Now keeping in mind that the sum of all angles in a triangle = 180. and rectangle = 360, so the increasing number of sides means adding 180 to it. So, 360 +180 +180+180+180+180+180 = 1440 degrees Bingoo :)

I know the formulae is n -2 * 180 but i find the first method more interesting and conceptual

simply in any one of the Equation Add the value of N After solving the Equation we will get the sum total of internal angles like 180(n-2)= 180( 10-2)=1440 woll be the correct answer.. n is the number of sides.!!!

Munish Sharma - 7 years ago
Kurt Espedilla
Feb 14, 2019

The total interior angle of a decagon is given by, Total interior angle = (n - 2)180 degrees. So, in a decagon the sum of all interior angle = 1440 degrees. Since the sides are equal, the interior angle at each vertex is = = 144 degrees. For any polygon, the total exterior angle is 360 degrees.

Ronica Duffus
Feb 16, 2018

The sum of the interior angles of a triangle = (nx180)-360 = 2160-360 =1440

Syed Hamza Khalid
Oct 10, 2017

Using the formula for the sum of the angles in a regular polygon:

( n 2 ) 180 = Sum of angles in a polygon \large \color{#3D99F6} (n - 2)180 = \text {Sum of angles in a polygon}

where n n is the number of sides...

(10 - 2) * 180 = 8 * 180 = 1440 degrees \therefore \text {(10 - 2) * 180 = 8 * 180 = 1440 degrees} = 1440 \large \color{#D61F06} =1440

It's called a decagon, by the way.

The sum of the internal angles for a polygon of n n sides is 180 ( n 2 ) 180(n-2) . Solving this for n = 10 n=10 , we find that the sum comes to 144 0 \boxed{1440^{\circ}} .

This is because a polygon of n n sides can be split into n 2 n-2 triangles (try it). As the sum of the angles of a triangle is 18 0 180^{\circ} , the total sum is simply 180 m 180m where m is the number of triangles.

A Former Brilliant Member - 6 years, 11 months ago
Andrew Tiu
Jun 19, 2014

(n-2)180 where n is the amount of sides. So: (10-2)(180)=1440

we can find any internal angle of polygon by the formula 180(n-2) where n is no. of sides

Ansh Bhatt
Jun 6, 2014

for any polygon the sum of the interior angles is 180 (n-2), n being the number of sides. here n is 10 so 180 (10-2) i.e. 180*8=1440

Mohd Sageer
Jun 3, 2014

180(n-2) for n sided polygen and it has 10 sides so n=10 then applying the above formulae, 180(10-2) = 180*8 = 1440 answer

did the same way.

Rhishikesh Dongre - 7 years ago
Padma Vathi
Jun 2, 2014

there r 10 sides. w.k.t sum of the interior angles is 180(n-2) =>180(10-2) 180(8) 1440

=180(n-2) =180(10-2) =180x8 =1440

Started at 180 for triangle, 360 for quadri, 540 for penta, 720 for hexa, and so on..... thus 180 (n-3 + 1) = 180 (10-3+1) = 180 x 8 = 1,440

Cesar Junio - 7 years ago

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