Mathematics
Two diagonals of a parallelogram ABCD intersect at O. If the area of the parallelogram is 20 cm2, then the area of ΔAOB is :
20 cm2
15 cm2
10 cm2
5 cm2
Theorems on Area
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Answer

The diagonals of a parallelogram divide it into four triangles of equal area.
So, Area(ΔAOB) = Area(∥gm ABCD)
=
= 5 cm 2.
Hence, option 4 is the correct option.
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Related Questions
ABCD is a rectangle and ABQC is a parallelogram. If the area of ΔABD is 5 sq. cm, then the area of the parallelogram is :
5 sq. cm
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P and Q are two points on the side DC of a ∥ gm ABCD. If the area of ΔPAB is 10 cm2, then the area of ΔQAB is :
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E is the mid-point of the side AB of a parallelogram ABCD. If the area of the ABCD is 60 sq. cm, then the area of ΔBDE is :
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Case Study :
A farmer was having a field in the form of a parallelogram ABCD. He divided the field into several parts by taking a point X on the side CD and joining it to vertices A and B. The farmer sowed wheat and pulses in equal portions of the field separately.
Based on the above information, answer the following questions :
1. By joining XA and XB, the field has been divided into how many parts?
(a) 2
(b) 3
(c) 4
(d) 52. The shapes of the parts obtained above are :
(a) triangles
(b) rectangles
(c) one triangle two squares
(d) none of these3. Area of ΔXAB is equal to :
(a) area of parallelogram ABCD
(b) area of parallelogram ABCD
(c) area of ΔADX + area of ΔBCX
(d) both 2. and 3.4. ΔABX and parallelogram ABCD are :
(a) On the same base DC
(b) On the same base AB and between the same parallels BC and AD
(c) On the same base AB and between the same parallels AB and CD
(d) On the same base CD and between the same parallels AB and CD5.If instead of taking point X on side CD, the farmer takes a point Y on side BC and joins YA and YD, then :
(a) area of ΔADY = area of ΔABY + area of ΔDCY
(b) area of ΔADY = area of parallelogram ABCD
(c) area of ΔADY = area of ΔABY
(d) area of ΔADY = area of ΔDCY