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Volume and Surface area of Cone (in Hindi)
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About Volume & Surface Area of Cone & Frustum of Cone is taught in this lesson. Also some questions based on topics taught are present in this lesson.

Mayank Agnihotri
B.Tech (ECE), Machine enthusiast, Inspired by an old hindi saying " Gyan baatne se badhta ha"

Unacademy user

  2. O CONE Cone is a solid or hollow body with a round base and pointed top. It is also formed by the rotation of a right angled triangle along any of its sides. . Volume=-x Base area x Height =7Tr2h * Slant height ()V+hz . Curved surface area 1 MTVr2 + h2 . Total surface area = curved surface area + Area of base = rl tTr2- (r + 1) Where, r Radius of base h Height and l Slant height heiyht

  3. FRUSTUM OF CONE If a cone is cut from the top to divide the cone into two parts upper part and lower part, then the lower part is called frustum of cone. Volume hR2 + rR) Slant height (l) -V(R - r)2 + h2 . curved surface area or lateral surface area- (R + r)! Total surface area = Area of top surface + bottom surface + Curved surface area heisht Where, r Radius of top, R- Radius of base (bottom), h- Height and l-Slant height

  4. Questions Ques 1. What is the volume of a cone having a base of radius 10 cm and height 21 cm? Sol. Volume of cone =rr2h 3 = 102 21 = 2200 cm3 Ans Ques 2. The diameter of base of a right circular cone is 6 cm and slant height is 14 cm, then what is its curved surface area? So Given, Diameter of a right circular cone 6 cm Radius of a right circular cone 3 cm slant height of a right circular cone ()14 cm =-= .: curved surface area of a cone-tri = 22 3 14 = 132 cm2

  5. Ques 3. The volume of frustum of a cone left after cutting it by a plane parallel to its base at half the height is how many times of the volume of cone. (1) (2) (3) (4) Sol. Volume of frustum of cone = 3 hfof+RF+TjRf) Here, Rf= r , Tj = 5 & hf = 2 (92+r2+ 1 Volume of frustum of cone =- 1 h [r2 3 2L4 7 Volume of cone =7TY2h Ans =

  6. Ques 4. Slant height of a cone is 10 cm and height Is 8 cm. Find the Curved surface area of cone. Sol. slant height (l) = Vr4hz radius (102-87-100-64 36 6 cm curved surface area of cone-Tri = 22 6 10 = 188.6 cm2 Ans I10 cm &h 8 cm given ]