Convex And Concave Polygon - Understanding Quadrilaterals - video Dailymotion

* Class: 7th, 8th * Subject: Mathematics * Chapter: Understanding Quadrilaterals

Transcript

00:00hello everyone welcome to Mudeera Shrine Academy we are doing quadrilaterals in this video I will

00:10be explaining convex and concave polygon so what is a polygon we have already done in last videos

00:17any closed figure is a polygon okay so this is a closed figure this is a polygon or we say if this

00:25is a closed figure this is also a polygon now when we talk about convex and concave polygon to

00:36understand we have diagonals in polygon right what are diagonals any line which touches two

00:44opposite vertices of a polygon or a quadrilateral quadrilateral is a figure having four sides right

00:51so it becomes the diagonal for example if this is a rectangle which is a quadrilateral with four

00:58sides and a polygon since it is a closed figure we have two diagonals here right if I name them as a

01:06a b c d then here a c and b d are two diagonals now any closed figure a polygon which is having

01:24diagonals which are completely inside the polygon that is in the interior okay that it is known as

01:32convex convex polygon whereas if we have any diagonal which is in the exterior of the polygon for example

01:41in the second figure we have a diagonal suppose I name this as a b c d here b c this b c is a diagonal

01:54which is in the exterior which is in the exterior of the polygon a b c d now since we have one diagonal

02:04in the exterior of the polygon this is called as concave polygon so to make it very clear if we have

02:14at least one diagonal in the exterior of a polygon okay which is outside the closed figure somewhere

02:21outside then it is concave polygon if we do not have any diagonal outside the polygon it is convex

02:28let us see one more diagram for both of them okay so suppose I have a

02:39say some diamond shape and here also we have two diagonals which are inside the polygon

02:48so this is convex so this is convex if I have a diagram somewhat like this

02:58and I am supposed to draw a diagonal here we have two vertices opposite and I can draw a diagonal which

03:08will be outside the closed polygon the closed figure then this will be called as concave polygon

03:17I hope this is clear thank you for watching

03:25you