Question

Who built the radius and height of a cone are in the ratio 4 ratio 3 the area of the base is 154 cm square find the area of the curved surface?

Answer 1

Answer:

192.5cm²

Step-by-step explanation:

let height be 3y and radius be 4y

area of base of a cone =πr²

                                       154 cm²=22/7×(4y)²

154 = 22/7×16y²

16y²= 154×7/22

y= 7×7/16

y= √7×7/16

y= 7/4

since radius= 4y ; y= 7/4

4y=4×7/4

radius=7cm

height=3y

3y=3×7/4

height=21/4

since l²=h²+r²

l=√(21/4)²+(7)²

l=√441/16+49

l=√441/16+784/16

l=√1225/16

l=35/4cm                          [35²=1225;4²=16]

Curved Surface Area of a cone=πrl

=22/7×7×35/4

=22x35/4

=192.5cm²