KnowledgeBoat Logo
|

Mathematics

The following diagram shows a pentagonal field ABCDE in which the lengths of AF, FG, GH and HD are 50 m, 40 m, 15 m and 25 m respectively; and the lengths of perpendiculars BF, CH and EG are 50 m, 25 m and 60 m respectively. Determine the area of the field.

The following diagram shows a pentagonal field ABCDE in which the lengths of AF, FG, GH and HD are 50 m, 40 m, 15 m and 25 m respectively; and the lengths of perpendiculars BF, CH and EG are 50 m, 25 m and 60 m respectively. Determine the area of the field. Area and Perimeter of Plane Figures, Concise Mathematics Solutions ICSE Class 9.

Mensuration

17 Likes

Answer

Area of figure ABCDE = Area of Δ ABF + Area of Δ AED + Area of Δ DHC + Area of trapezium BFHC

Area of Δ ABF = 12\dfrac{1}{2} x b x h = 12\dfrac{1}{2} x AF x BF

= 12\dfrac{1}{2} x 50 x 50 m2

= 25 x 50 m2

= 1250 m2

Area of Δ AED = 12\dfrac{1}{2} x b x h = 12\dfrac{1}{2} x AD x GE

= 12\dfrac{1}{2} x (AF + FG + GH + HD) x GE

= 12\dfrac{1}{2} x (50 + 40 + 15 + 25) x 60 m2

= 130 x 30 m2

= 3900 m2

Area of Δ DHC = 12\dfrac{1}{2} x b x h = 12\dfrac{1}{2} x HD x CH

= 12\dfrac{1}{2} x 25 x 25 m2

= 12.5 x 25 m2

= 312.5 m2

Area of trapezium BFHC = 12\dfrac{1}{2} (sum of parallel sides) x distance between the parallel sides

= 12\dfrac{1}{2} (BF + CH) x FH

= 12\dfrac{1}{2} (BF + CH) x (FH + GH)

= 12\dfrac{1}{2} (50 + 25) x (40 + 15) m2

= 12\dfrac{1}{2} x 75 x 55 m2

= 37.5 x 55 m2

= 2062.5 m2

Thus, area of figure ABCDE = 1250 + 3900 + 312.5 + 2062.5 m2

= 7525 m2

Hence, the area is 7525 sq. m.

Answered By

12 Likes


Related Questions