ICSE Class 9 Answered
Prove that a line joining the mid points of the parallel sides of a trapezium divides it into two equal parts
Asked by aswani1617 | 18 Sep, 2018, 23:02: PM
G![](https://images.topperlearning.com/topper/tinymce/imagemanager/files/8fb2bd23bf0e7eb84fcea758ec7542a45ba21179ba50e0.01603668ATE19918MathsPic01.png)
![](https://images.topperlearning.com/topper/tinymce/imagemanager/files/8fb2bd23bf0e7eb84fcea758ec7542a45ba21179ba50e0.01603668ATE19918MathsPic01.png)
Given : ABCD is a Trapezium
Point H and G are the mid point of parallel sides.
Construction: AE and BF are the height of the trapezium.
To prove : Area of
AHGD = Area of
HBCG
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
Let us assume that The given Trapezium is an isosceles Trapezium, with AD = BC
Here,
AH = HB and DG = GC ....since Point H and G are the mid-point of AB and CD.
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
(since AE = BF ..since AB || CD and AE and BF are perpendicular to DG and GC respectively)
EG = AH .......(sides of a reactangle)
HB = GF ......(side of a rectangle)
Therefore Area of a
AHGE = Area of a
BHGF ....(i)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
In ΔADE and ΔBFC
AE = BF
AD = BC
and
AED =
BFC = 900
![angle](https://images.topperlearning.com/topper/tinymce/cache/b26763ff7db2ff496dbc2682f516d58a.png)
![angle](https://images.topperlearning.com/topper/tinymce/cache/b26763ff7db2ff496dbc2682f516d58a.png)
Therefore ΔADE
ΔBFC ...(RHS )
![approximately equal to](https://images.topperlearning.com/topper/tinymce/cache/f4a08dc1ae961f7d1cda17c55bf623f6.png)
Therefore ΔADE = ΔBFC.......(ii)
Area of a
AHGD = ΔADE +
AHGE and
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
Area of a
BHCG = ΔBFC +
BHGF
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
from (i) and (ii), we get
Area of
AHGD = Area of
HBCG
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
![begin mathsize 16px style square end style](https://images.topperlearning.com/topper/tinymce/cache/a458f9cf29bce1a38e8299fb18eda475.png)
Answered by Yasmeen Khan | 19 Sep, 2018, 14:37: PM
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