Check sibling questions

Ex 13.1, 3 - A toy is in form of a cone of radius 3.5 cm - Surface Area - Added

Ex 13.1, 3 - Chapter 13 Class 10 Surface Areas and Volumes - Part 2
Ex 13.1, 3 - Chapter 13 Class 10 Surface Areas and Volumes - Part 3 Ex 13.1, 3 - Chapter 13 Class 10 Surface Areas and Volumes - Part 4


Transcript

Ex 13.1, 3 A toy is in the form of a cone of radius 3.5 cm mounted on a hemisphere of same radius. The total height of the toy is 15.5 cm. Find the total surface area of the toy. Total surface area of toy = Curved Surface area of hemisphere + Curved Surface area of cone Curved Surface area of hemisphere Radius of hemisphere = radius of cone = r = 3.5 cm Curved surface area of hemisphere = 2 2 = 2 22/7 (3.5)2 = 2 22/7 3.5 3.5 = 2 22 0.5 3.5 = 77 cm2 Curved surface area of cone Curved surface area of cone = Radius of cone = r = 3.5 cm Height of cone = Total height of toy radius of hemisphere = 15.5 3.5 = 12 cm Now, we find slant height (l) We know that l2 = h2 + r2 l2 = (12)2 + (3.5)2 l2 = (12)2 + (7/2)^2 l2 = 144 + 49/4 l2 = (144(4) + 49)/4 l2 = (576 + 49)/4 l2 = 625/4 l = (625/4) l = ( 25 ^2/2^2 ) l = 25/2 l = 12.5 cm Curved surface area of cone = r = 22/7 3.5 12.5 = 22 0.5 12.5 = 137.5 cm2 Total surface area of toy = Curved Surface Area of hemisphere + Curved Surface Area of cone = 77 + 137.5 = 214.5 cm2 Hence, total surface area of the toy = 214.5 cm2

Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.