QUADRILATERAL (LECTURE 2)

QUADRILATERALS  

LESSON 2
5th May

Few Instructions 

Welcome you all once again!

1. Note down  the work in your register on a regular basis.

.2 AS ALREADY MENTIONED,YOU CAN USE ANY NOTEBOOK AVAILABLE AND SUBMIT SEPARATELY ONCE THE SCHOOL REOPENS.

3. Take your  Mathematics Register

4. Write  the  name of the chapter   QUADRILATERALS and todays date 

Guidelines for the Blog

·         The text in BLUE, is to be written in your register

·         The text in Red is to be viewed by clicking on it

·         The text in green is to be practiced for home work

        · Feel free to clarify your doubts by dropping a comment before going ahead in the lesson

yesterdays  learning  outcomes:-

 I  will be able to recall 

• simple closed curve 
• polygon and its types 
• evaluate number of diagonals in a polygon.

Todays learning outcomes :-

I will be be able evaluate

• sum of interior angles of a polygon 
• sum of interior angles of a quadrilateral
• Evaluate the unknown angle  of quadrilateral

As we know that the sum of angles of a triangle is 180°

What is the sum  of angles of a quadrilateral ?..........(180°/ 360°)

Why is the sum of angles of a quadrilateral , 360° ?

 click the link given below

  SUM OF ANGLES OF QUADRILATERAL

Now we know ,SUM OF INTERIOR ANGLES IN A QUADRILATERAL  IS 360 °

L Solve the question given below:

 what did we notice ,the given set of angles form a quadrilateral only in the  (1) case

                                why ?                        ................................

                                                                          

    All of you must have got it correct ................................

 Now you will be able to understand 

 see  Q3  Ex 3.1 ( To be done in HOMEWORK) 

SUM OF INTERIOR ANGLES OF POLYGONS  CAN ALSO BE CALCULATED BY( USING FORMULA )

Sum of interior angles of polygon = ( n-2) x 180°  ,where

 n = number  of sides

lets solve Q4  ( a, b ) (class work)

Q4 (c,d )  is for  HOMEWORK

 As we know , SUM OF INTERIOR ANGLES IN A QUADRILATERAL  IS 360 °

L    

 LET SEE THE QUESTIONS GIVEN BELOW 

                                   'Find the value of 'd' and 'x  

What property is used to calculate  angle 'd'....................



What property is used to calculate  angle 'x'....................

You are right  'angle sum property of quadrilateral'

Lets do Q6  ( a,d )      Ex.3.1 

  

 (d) Here the polygon is not quadrilateral. Its  pentagon .

 so number of sides = 5

∴sum of interior angles of a pentagon = (n - 2) x 180° 

                                                                   = (5 -2 ) x 180 = 540° 

   The figure is regular pentagon ,so its  sides are equal.
    Thus all angles are also equal. 

     let one angle be  'x'
         Each interior angle  =       5x =540°
                                                      x=  540°/ 5
                                                      x =  108°
                                            

lets solve Q7 (a)  class work

     

Excercise 3.1

Q3

Q4 (c,d)

Q6 (b,c)

 Q7 (b)

   
     Thats all for today 

  Have a good day

CLICK THE GIVEN LINK          lets try