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Probability

Question
CBSEENMA9003432
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The curved surface area of a right circular cone is 12320 cm2. If the radius of its base is 56 cm, find its height.

Solution

Let the height of the right circular cone be h cm. r = 56 cm Curved surface area = 12320 cm2 ⇒    πrl = 12320
rightwards double arrow space space space space πr square root of straight r squared plus straight h squared end root equals 12320 rightwards double arrow space space space space 22 over 7 cross times 56 cross times square root of left parenthesis 56 right parenthesis squared plus straight h squared end root equals 12320 rightwards double arrow space space space square root of left parenthesis 56 right parenthesis squared plus straight h squared end root equals 70
⇒    (56)2 + h2 = (70)2
| Squaring both sides
⇒    h2 = (70)2 – (56)2
⇒    h2 = (70 – 56)(70 + 56)
⇒    h2 = (14)(126)
⇒    h2= (14)(14 x 9)
⇒    h = 14 x 3 = 42
| Extracting square root
Hence, the height of the right circular cone is 42 cm.


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(i) Which box has the greater lateral surface area and by how much?

A cubical box has each edge 10 cm and another cuboidal box is 12.5 cm long, 10 cm wide and 8 cm high.

(i) Which box has the greater lateral surface area and by how much?

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