Multiple choice

Find the area of the iron sheet required to prepare a cone 20 cm. high with base radius 21 cm. 20 सेमी. ऊंचे शंकु और 21 सेमी. आधार त्रिज्या वाले शंकु को बनाने के लिए आवश्यक लोहे की चादर का क्षेत्रफल ज्ञात कीजिए।

  1. 2200 cm2/ सेमी2

  2. 3300 cm2/ सेमी2

  3. 2277 cm2/ सेमी2

  4. 3366 cm2/ सेमी2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To find the area of iron sheet needed, we calculate the total surface area of the cone: πr(l+r) where r=21 cm and l=√(r²+h²)=√(441+400)=29 cm. Using π=22/7: Area = (22/7)×21×(29+21) = 66×50 = 3300 cm². Option A is only the curved surface area, C is incorrect, and D includes an extra factor.

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