Activity & Practical on Ratio of Areas of Two Similar Triangles| Class 10th level | edugrown

  • Pythagoras’ theorem: In a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.

Aim

  • To verify “The ratio of the areas of two similar triangles

Objective

  • To verify “The ratio of the areas of two similar triangles is equal to the ratio of the square of their corresponding sides” by performing an activity.

MATERIALS REQUIRED

Chart paper, construction box, coloured pens, a pair of scissors, fevicol.

THEORY

  • In a right-angled triangle the square of hypotenuse is equal to the sum of squares on the other two sides.
  • Concept of a right-angled triangle.
  • Area of square = (side)2
  • Construction of perpendicular lines.

PROCEDURE

      1. Take a white chart paper and cut a ∆ABC with 
        AB=6cm,  
         BC=6cm, 
         CA=6cm
         
        Mark five points P1,P2,P3,P4,P5 at a distance of 1 cm on side AC and
        Q1,Q2,Q3,Q4,Q5 at a distance of 1 cm on side AB. ( Image 1)
         
         
                                                                                  
         
        Join P1Q1,P2Q2,….P5Q5  
         
         
        2. Draw parallel line to  AC from Q1, Q2…. and parallel line to AB from P1, P2,.( Image 2)
         
                                                                                 
         
        This ∆ ABC is divided into 36 similar and equal in area of triangles.
         
        Construct a  ∆ PQR 
        with PQ= Half of AB
                PR=Half of AC  
                QR=Half of BC on other chart paper
         
        3. Mark D1,D2  and E1,E2 on sides PQ and PR ( Image3)
         
                                                                                    
         
        4. Divide  ∆ PQR into 9  similar and equal in areas triangles ( Image 4)
         
                                                                                  

Observation

Area of   ∆ABC=Area of 36 smaller triangles
Area of  ∆ PQR=Area of 9 smaller triangles
 
 

Result

It is Verified that the ratio of the areas of two similar triangles is equal to the ratio of the square of their corresponding sides.


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