CBSE Class 9 Answered

I want all three answers from figure I.e4,5,6 figure is somewhat blurd so please see carefully and answer

Asked by md775016 | 28 May, 2017, 03:41: PM

Expert Answer

begin mathsize 18px style Total space cost space equals space Rs. space 176 space Rate space of space charge space equals space 25 space paise space per space sq. cm space equals space Rs. space 0.25 space per space sq. cm space space space Total space cost space of space painting space cone space equals space Total space surface space area space of space cone cross times space Rate space of space charge space rightwards double arrow Total space surface space area space of space cone space equals space fraction numerator Total space cost space of space painting space cone space over denominator space Rate space of space charge end fraction equals space fraction numerator 176 over denominator 0.25 end fraction equals space 704 space sq. cm space space Let space radius space of space cone space be space straight r space cm space slant space height space left parenthesis straight l right parenthesis space equals space 25 space cm space space Total space surface space area space of space cone space equals space πr left parenthesis straight r plus straight l right parenthesis space rightwards double arrow 704 equals πr left parenthesis straight r plus straight l right parenthesis space rightwards double arrow 704 equals fraction numerator 22 straight r left parenthesis straight r plus 25 right parenthesis over denominator 7 end fraction rightwards double arrow 704 cross times 7 over 22 equals straight r squared plus 25 straight r space rightwards double arrow 224 space equals straight r squared plus 25 straight r space rightwards double arrow 0 space equals straight r squared plus 25 straight r space minus 224 space rightwards double arrow space 0 space equals space straight r squared plus 32 straight r minus 7 straight r minus 224 space rightwards double arrow 0 space equals space straight r left parenthesis straight r plus 32 right parenthesis minus 7 left parenthesis straight r plus 32 right parenthesis space rightwards double arrow 0 equals space left parenthesis straight r minus 7 right parenthesis left parenthesis straight r plus 32 right parenthesis rightwards double arrow 0 space equals space straight r minus 7 space or space 0 space equals space straight r plus 32 rightwards double arrow straight r space equals space 7 space or space minus 32 space space straight r space cant space be space minus 32 space since space the space radius space cannot space be space negative Therefore comma space radius space of space cone space equals space 7 space cm space space By space Pythagoras space Theorem comma space height space of space cone space equals space square root of left parenthesis straight l squared minus straight r squared right parenthesis end root space equals square root of left parenthesis 25 squared minus 7 squared right parenthesis end root equals square root of 625 minus 49 end root equals square root of 576 space end root equals 24 space cm space space Therefore comma space volume space of space cone space equals space fraction numerator πr squared straight h over denominator 3 end fraction equals space fraction numerator 22 cross times 7 cross times 7 cross times 24 over denominator 7 cross times 3 end fraction equals 1232 space cu. space cm Dear space student comma space straight I space have space answered space the space question space 4. space Kindly space post space only space 1 space question space per space query. end style

Answered by Rebecca Fernandes | 24 Nov, 2017, 12:04: PM

CBSE Class 9 Answered

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Surface Area of a Cone

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CBSE Class 9 Answered

Concept Videos

Surface Area of a Cone

Surface Area of a Cone

Surface Area of a Cone

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