最佳回答取４０分：幾條關於volume of cirxular cone既問題=)

以下有兩條問題想請教下
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第一條：
A piece of ice in form of an inverted right circular cone has radius of 4.5 cm and slant height 3 cm as shown below is resulted. Find the volume of the frustum correct to 3 significant figures.

圖片參考：http://i149.photobucket.com/albums/s72/zivsinglung/SSL10816.jpg

第二條：
Figure (a) below shows a solid right circular cone. O is the vertex and Pis a point on the circumference of the base. The area of the curved surface area 135πc㎡ and the radius of the base is 9 cm.
Figure (a):

圖片參考：http://i149.photobucket.com/albums/s72/zivsinglung/SSL10819.jpg


(a) Find the length of OP.
(b) Find the height of the cone.
Figure (b):

圖片參考：http://i149.photobucket.com/albums/s72/zivsinglung/SSL10820.jpg

(c) The cone in Figure (a) is cut into two portion by a plane parallel to its base. The upper portion is a cone of the base radius 3 cm. The lower portion is a frustum of height x cm.
(i) Find the value of x.
(ii)A right cylindrical hole of radius 3 cm is drilled through the frustum, see Figure (b). Find the volume of the solid remained in the frustum.
希望大家幫下手啦
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