Question

two cones with same base radius 15 cm and height 20 cm are joined together along their base. Find the surface area of the shape so formed. ( use π=3.14)?

Answer 1

The figure will look somewhat like this.

By Pythagoras Theorem,

${l}^{2} = {h}^{2} + {r}^{2} \\ {l}^{2} = {15}^{2} + {20}^{2} \\ {l}^{2} = 225 + 400 \\ l = 25$




So, the Total Surface Area of the shape so formed =

$2 \pi rl$

= 2 × 3.14 × 15 × 25
= 2355 so. Cm