Geometry - 2D Shapes
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00:00Hi kids, today we will identify various shapes depending on their geometric properties.
00:10So let's get started.
00:13Polygon A polygon is a 2D figure with three or more
00:22straight sides.
00:25So let's mark which of the following figures are polygons.
00:32We just learned polygons have only straight sides or edges, so this figure is not a polygon.
00:44This is a polygon as it has all straight sides.
00:51This figure is not a polygon as its edges are not straight.
00:58This is a polygon as its all edges are straight.
01:05Yeah, this too is a polygon.
01:09This is also a polygon.
01:13This is also a polygon.
01:17This is not a polygon as it doesn't have straight edges.
01:23This is a polygon as it has all straight edges.
01:29This is not a polygon.
01:33So we have selected all the polygons out of these shapes.
01:39Now let's learn what are regular polygons.
01:43A polygon where all the sides and internal angles are same is a regular polygon.
01:52Example This is a polygon where all the sides are
01:57same.
01:59Also all the internal angles are same.
02:03So it's a regular polygon.
02:07Here is another example.
02:10All the sides and angles are same in this figure.
02:15So this is a regular polygon.
02:20Now which of the following figures are regular polygons?
02:24Yeah, these figures are regular polygons out of these as these figures have all sides and
02:33angles same.
02:37Now let's learn about irregular polygons.
02:43Are these regular polygons?
02:45No, they are not regular polygons as neither their vertices nor their internal angles are
02:54same as they are irregular polygons.
02:59Now which of the following figures are irregular polygons?
03:04Yeah, this, this and this.
03:10These three figures are irregular polygons out of these.
03:16Now let's learn what are quadrilaterals.
03:21The polygons that have four sides are known as quadrilaterals.
03:27Here are some polygons.
03:30Let's figure out which of the following are quadrilaterals.
03:36We know quadrilaterals have exactly four sides, neither more nor less exactly four sides.
03:47Here these shapes out of all the shapes have four sides.
03:52So these are quadrilateral.
03:55Now let's learn what are parallel lines.
04:01Lines that do not meet each other even on extending are known as parallel lines.
04:09Parallel lines are always equidistant from each other.
04:14They are never meet each other no matter how long we extend them.
04:23These figures have one or more pair of parallel lines.
04:28They can never meet each other and the distance between them always remains the same.
04:35Here are some polygons.
04:39Let's see which of these figures have one or more parallel lines.
04:45This figure has a pair of parallel lines.
04:50This pair of lines is parallel.
04:53That is, these lines can never meet each other no matter how long we extend them.
05:00And this pair of lines is not parallel.
05:04They will meet each other if you extend them, like this.
05:11This figure has two pairs of parallel lines.
05:17This figure also has two pairs of parallel lines.
05:24This figure does not have any parallel lines.
05:30This figure has many pairs of parallel lines.
05:36This figure has two pairs of parallel lines.
05:42This figure does not have any parallel lines.
05:48This figure has many pairs of parallel lines.
05:53So we have marked all the shapes that have one or more pairs of parallel lines.
06:01Now let's learn what are intersecting lines.
06:06Points that meet each other at a single point are called intersecting lines.
06:12A minimum of two lines are required for intersection.
06:19The point where two lines meet is called the point of intersection.
06:25Here the lines L and M meet at point Q.
06:32Here Q is the point of intersection and lines L and M are intersecting lines.
06:42Now which of the following figures have intersecting lines?
06:47Only these three figures have intersecting lines.
06:51The other three figures do not have any intersecting lines.
06:57These are the point of intersection in these figures with intersecting lines.
07:05Now let's learn what are congruent figures.
07:10Figures that have same shape as well as same size are called congruent figures.
07:18Let's figure out which of the following figures are congruent figures.
07:24Yeah, these figures are congruent as they have same shape as well as same size.
07:33Now let's learn what are similar figures.
07:38Figures that have same shape are called similar figures.
07:43Size can be same or different but shape must be same.
07:51Such figures are called similar figures.
07:56These are a few examples of similar figures.
08:02Here in case of these stars they have same shape so they are similar figures.
08:10Their size is also same.
08:15In case of these two pentagons shape is same so they are similar but the size is different.
08:24In case of these arrows shape is same so these are similar figures although their size is different.
08:35So we learned that figures with the same shape are similar their size can be same or different.
08:44Which of the following figures are similar figures?
08:49Yeah, these figures are similar as they have same shape.
08:57Remember if the figures have both same shape as well as size they are both similar as well as congruent.
09:08As similar figures means same shape and congruent figures means same shape as well as same size.
09:18So all congruent figures are similar too but all similar figures are not congruent
09:26as they may or may not have same size too.
09:32Now let's learn what are symmetrical figures.
09:37Figures that can be folded or divided into half so that the two halves can
09:44completely cover each other are called symmetrical figures.
09:50These are examples of symmetrical figures.
09:54Now you may go ahead and take a quiz to learn more.
09:58Bye-bye.