RD Sharma - Mathematics

Book: RD Sharma - Mathematics

Chapter: 20. Mensuration-I (Area of a Trapezium and a Polygon)

Subject: Maths - Class 8th

Q. No. 19 of Exercise 20.2

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19

In Fig. 20.38, a parallelogram is drawn in a trapezium, the area of the parallelogram is 80 cm2, find the area of the trapezium.



In ΔCEF


CE = 10 cm and EF = 6cm


Using pythagorous theorem:


CE2 = CF2 + EF2


CF2 = CE2 - EF2


CF2 = 102 - 62


CF2 = 100-36


CF2 = 64


CF = 8 cm


Area of parallelogram = 80 cm2


Area of trapezium = area of parallelogram AECD + area of area of triangle CEF


Area of trapezium =


Area of trapezium =


Area of trapezium = 80 + 48 = 128 cm2


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