Q. 204.2( 11 Votes )
Given: Height of cone = 30 cm
To find: Height above the base of section.
The volume of cone =
Given the height of the cone, H = 30 cm
Let the small cone which is cut off at a height ‘h’ from the top.
Let the radius of the big cone be R cm, and the small cone is r cm.
The volume of the big cone,
The volume of the smaller cone,
Given according to the question,
Now, in ∆KCB and ∆KDM
∠CKB = ∠DKM (common)
∠KCB = ∠ KDM = 90°
∴ ∆KCB~∆KDM (by AA-similarity)
Putting the value in equation (1), we have
Thus the height above the base at which the section is made = 30-10 = 20 cm
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