Question

a window pane is in the shape of regular octagon find the cost of polishing the window pane at rupees 2.50 per m

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Answer 1

Step-by-step explanation:

octagon can be divided into 8 triangles similar to ΔOBC and the angles are shown in figure.

Area of octagon = 8×(1/2)×a×h = 8×(1/2)×a×(a/2)×tan67.5 ≈ a2 × 4.83 m2

Cost of polishing = a2 × 4.83 × 2.5 = 12.08×a2