very urgent......... The frame of a lampshade is cylindrical in shape. it has base diameter 28cm and height 17cm. It is to be covered with a decorative cloth. A margin of 2 cm is to be given for floding it over top and bottom of the frame. If 1/12 of cloth is wasted in cutting and pasting, find how much cloth is required to be purchased for covering the frame. please give proper answer of this question.
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As margin is 2cm is given at top and bottom, the effective height to be considered in this case should be 17cm+2×2cm [2cm for bottom and 2cm for top].
Thus, height =21cm (=h)
and radius =28/2 =14cm (=r)
Now, the area of this cloth =2πrh
=2×(22/7)×14×21 sq cm.
=1848 sq cm.
We also know that 1/12 is wasted in cutting. Thus, actually used cloth is 11/12 of the original cloth.
From this we can write;
11/12 of original cloth =1848 sq cm.
Hence, whole (12/12 = 1) of the original cloth =1848×(12/11) sq cm.
=168×12 sq cm.
=2016 sq cm. [Answer]
Hope this helps. For more you can comment please. Thanks!
Thus, height =21cm (=h)
and radius =28/2 =14cm (=r)
Now, the area of this cloth =2πrh
=2×(22/7)×14×21 sq cm.
=1848 sq cm.
We also know that 1/12 is wasted in cutting. Thus, actually used cloth is 11/12 of the original cloth.
From this we can write;
11/12 of original cloth =1848 sq cm.
Hence, whole (12/12 = 1) of the original cloth =1848×(12/11) sq cm.
=168×12 sq cm.
=2016 sq cm. [Answer]
Hope this helps. For more you can comment please. Thanks!
abhishekabhishek:
very very thank you
i have a doubt please
if 1/12 cloth is going to be wasted, then shouldn't an extra length of cloth to be added to the total material required?
this is urgent , whoever can answer
Yes, Please wait! It will be clear.
That extra length is already added. That is why the used cloth is 11/12 of the original cloth taken. You can also say -― Let x be total cloth. Since x/12 is wasted, the actually used for lamp shade is 11x/12, which is also the surface area of the lamp shade.
If still not clear then please message me. Thanks!
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