Question

If the radii of circular ends of a frustum of a cone are 20 cm and 12 cm and its height is 6 cm,then find the slant height of frustum (in cm).
​

Answer 1

Answer:

135.71 cm^2

Step-by-step explanation:

We have

r1=14cm;r2=6cm;h=6cm

Let l be the slant height of the frustum. 

Then l=h2−(r1−r2)2⇒l=36+64=10cm=π(r1+r2)

Lateral surface area =722×(14+6)cm2=628.57cm2

total surface area =π{r12+r22+(r1+r2)l}

                              =722×(196+36+20×10)cm2=1357.71cm2