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In this video we are going to focus on this question.
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Now given a trapezium shaped road.
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So this is the surface area of this road.
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Now the trapezium a b c d e f here there are three section first triangle bcd second rectangle a b d e and third triangle a f e.
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Now the angle c b d that is equal to theta and angle e a f that is equal also theta.
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Now using the using the trigonometric identities identities in triangle bcd and triangle a f e.
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So bc equal a f that is equal cos theta upon 1 and cd equal a f that is equal sin theta upon 1.
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Now find the cross section area of this trapezium find the now find the cross section area of this trapezium.
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So area a that is equal half of multiply by cd times bd.
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So this area is triangle bcd plus the area of rectangle ab ef that is equal ab times bd plus half of multiply by ef times e.
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So this area is triangle a f e.
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Now the cross section area a that is equal half of times cos theta times sin theta plus 1 times cos theta plus half of cos theta times sin theta.
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Now the cross section area a that is equal cos theta times sin theta plus cos theta here area a that is equal cos theta is common now 1 plus sin theta.
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So cross section area a that is equal cos theta times 1 plus sin theta.
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Now we found the volume of this trapezium road.
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So volume b that is equal area times length.
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So in this equation length l that is equal 18 unit...