Question

Determine the area of the following polygons.
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Answer 1

Area of the closed figure = ar(ABCD) × 2 + ar(EHCD).

[because ABCD = EHGF; compare their heights and sum of || sides.]

We know,

Area of trapezoid = ½(a + b)h

[Sum of parallel sides × Distance between them]

Area of rectangle = l × b

[Product of length and breadth]

∴ Area of figure:-

2[½(a + b)h] + lb =

= (a + b)h + lb

= (10 + 20)(10) + (50)(10) sq. units

= 300 + 500 sq. units

= 800 sq. units

N.B.:-

The alternative way of finding the area is to find the area of rectangle ABFG and then subtract the twice of that of trapezoid CBGH.

There are many such ways! Discover more!