How do you find the interior angle of a polygon?

Question

How do you find the interior angle of a polygon? Using Triangles?

I mean like if there are five sides and you know 4 of the angles and u need to find out what the last one is?

or is this right?
(n-2) x 180
say this is an example:
angles i know are:
100(degrees)
123
94
78

i need to find out the last one (n)

so i did
(5-2)x180
=540

then i added up all the angles i know: equaling 395

took 395 away from 540 and got 145

so n=145

please reply soon! x

Answer 1

You have the correct method, always assuming that n is the number of sides of the polygon, and that you are working in degrees rather than in radians. (If that's too technical, don't worry!)

I have an honours degree in maths. so I like to think I know about these things.

Answer 2

Let the exterior angle be x Interior angle = 4x 4x + x = 180 5x = 180 x = 36 Sum of exterior angles of a regular polygon is always 360 So no of sides = 360/36 = 10 sides ANSWER

Answer 3

This is simple Total is 360, degrees, no matter what, any polygon of any number of sides.

So if you know all but one only then add up all and say that is "X" degrees then the unknown is 360 - X = "y"
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You can draw it and measure it also.
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If it is a regular polygon then and do not know any angles then 360/n degrees, Hexagon has six angles so 360/6 = 60.

Octagon has 8 so 368/8 = ?

Answer 4

you're right