Q 8, Ex 12.1 - Surface Areas And Volumes - Chapter 12 - Maths Class 10th - NCERT

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✔️ Class: 10th
✔️ Subject: Maths
✔️ Chapter: Surface Areas And Volumes
✔️ Topic Name: Q 8, Ex 12.1

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0:00 Question 8

[kabirsingh]

Always remember surface area will only increase if something is removed.
Take surface area as area you can touch. If something is removed from a solid now you can touch more surface area and hence surface area will add up

[zainabrather]

Maam we have to find the remaining solid so we need to subtract curved surface area of conical part from total surface area of solid

[tanuawasthy]

mam why you have added the CSA, CSA of cone and circle rather it should be substracted from it to get the remaining part??

[pareshbarman]

Ma'am agar remaining Area find krna hai to iska matlab to cone ko cut kia gya hai then cone ka area to subtract hona tha bt isme add kio kiya gya hai...?

[mdmahtavalam]

mam i m very confused bcz question asked about remaining part so why do we add all this thing why dont we do tsa of remaining = csa of culinder + pie r square _ csa of cone

[sujeetaman]

Thanks. Your teaching way is so easy. 👍👍

[manojsingour]

Mam but why we are adding we should subtract it for the remaining area

[DeepakChoudhary-oyld]

I saw same question in many channels but everyone is adding the area of Cone ...but in the question they said we have to Find out the remaining area...and koii bh channel valid reason nhi bta rhe h...🙁🙁🙁

[aditiambani]

Thanks for this answer this answer helpful for all

[kabirsingh]

Curved surface of cone will be embedded in the figure.Any depression or cut will increase the surface area of solid figure. That's why we have to add it.
Guys !!! See the thing is the cylinder is solid.Imagine it as wooden block.Imagine a 3D figure.
Remove a cone from it.Now you would realize the curved portion of cylinder and basal circle remains as it is.
The removed cone will increase the area because any irregularity in the figure increase the surface area.Irreguality here is removed cone.
Take area as which you can touch in the remaining figure.
And you can touch the curved surface area of cylinder, the basal circular portion and now the curved surface of cone is embedded in it.
That's why we have to add the curved surface area of cone.
I hope it helps.
Imagination is key in solving this type of que.

[drsatishkumar]

I also want to know why you have added csa whynot subtracted ?

[HarshGupta-nsfx]

Man,
Why we are adding πr square, we should subtract πr square because there will be two base in same plain one of cone and second of cylinder.

And mam please reply to our queries it's vital for our knowledge without clarifying queries problem became more difficult and jumbled.

[ganeshmurthy]

Mam the easiet way juct find tsa of cylinder ... coz the cone is in it so it just gets add up to the cylinder

[laxmandhakad]

Ma'am I Think we should subtract TSA of cone from the TSA of cylinder

[ramnareshupadhyay]

mam i did not understand this question why we add csa

[lakhwinderkatal]

mam galat Kia huya hai apne...
cylinder m se cone nikala gya hai to minus hoga

[farheensaifi]

Why u take slant height in metre but in question they are said that find the remaining area of solid to the nearest cm square

[reenareetasahu]

thanks man for teaching, but I have doubt in question 8 by finding remaining part

[Sanjayverma-fhmq]

Mam yeah sad kuch to cm. Mai tha fir apne slant height m mai Ku nikale fir ans cm mai ??
Mam please reply

[salmaaftab]

Mam plzzz correct the Unit of Slant height it may cause confusions to the viewers Plz note the unit carefully.
I Hope you understand
Thank you🙏