Question

a window pane is in the shape of a regular octagonfind the cost of polishing the window pane
ane at rate Rupees 2.50 per metre square
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Answer 1

Step-by-step explanation:

A window pane is in the shape of regular octagon. The cost of polishing the window pane at $2.50perm² is $477.50.

To find the total area of the figure.

The octagon in the figure includes 2 trapeziums.

Each trapezium has a height 'h' of 5m , side of 'b' = 7m and another side 'a' = 13m.

So, the area of trapezium is given as (a+b)h × (1/2)

= (13+7) × 5 × (1/2) m^2

= 50 m^2

Total area of the 2 trapezium = 2 × 50 = 100 m^2.

There is a rectangle with  length 'l' = 13m and breadth 'b' = 7m between the 2 trapeziums.

Its area is l × b = 13 × 7 = 91 m^2.

Hence, the total area of the figure = (100 + 91)m^2 = 191 m^2

Cost per m^2 = $2.50

So, cost of 191m^2 = $(2.50 × 191) = $477.50

Hence, the total cost is $477.50