If R is the radius of the base of the hat, then the total outer surface area of the hat is
(a) πr(2h + R)
(b) 2πr(h + R)
(c) 2πrh +πR²
(d) None of these
Solution:
The total outer surface area is the sum of three areas marked above:
Total Outer Surface Area = Surface Area 1 + Surface Area 2 + Surface Area 3
Total Outer Surface Area = πr² + 2πrh + πR² - πr² = 2πrh + πR²
The correct answer is choice choice ( c ).
✦ Try This: If R is the radius of the base of the hat, then the surface area of the hat rim is (a) πr(2h + R), (b) 2πr(h + R), (c) 2πrh + πR², (d) π(R² - r²)
The outer surface area of the hat’s rim is:
Total Outer Surface Area of hat rim = Surface Area 3
Total Outer Surface Area of the hat rim= πR² - πr²
The correct answer is choice choice ( d ).
☛ Also Check: NCERT Solutions for Class 8 Maths Chapter 11
NCERT Exemplar Class 8 Maths Chapter 11 Problem 28
If R is the radius of the base of the hat, then the total outer surface area of the hat is (a) πr(2h + R) (b) 2πr(h + R) (c) 2πrh + πR (d) None of these
Summary:
If R is the radius of the base of the hat, then the total outer surface area of the hat is 2πrh + πR²
☛ Related Questions:
- A cube of side 4 cm is painted on all its sides. If it is sliced in 1 cubic cm cubes, then number of . . . .
- A cube of side 5 cm is cut into 1 cm cubes. The percentage increase in volume after such cutting is . . . .
- The surface area of a cuboid formed by joining two cubes of side ‘a’ face to face is _________