Question

A right cone has radius 5 ft and slant height 9 ft. The radius and slant height are both multiplied by 1/2. Which of the following correctly describes the effect on the surface area?

Answer 1

The surface area is multiplied by 1/4.

Explanation:

Lucky guess on my quiz haha

Answer 2

101.07ft^2

Explanation:

Given data

radius= 5ft

h= 9ft

When the radius and height are both multiplied by 1/2

radius= 5/2ft = 2.5ft

height= 9/2 ft= 4.5ft

The expression for the surface area of the cone is

A=πr(r+√h^2+r^2)

Substiute

A= 3.142*2.5(2.5√4.5^2+2.5^2)

A= 7.855(2.5√20.25+6.25)

A= 7.855(2.5√26.5)

A= 7.855(2.5*5.147)

A=101.07 ft^2

Hence the surface area is 101.07ft^2