Two cones with same base radius 8 cm and height 15 cm are joined together along their bases. Find the surface area of the shape so formed.

When two identical cones are joined along their base, the shape so formed will be as shown in figure

So,

Total surface area of shape formed = Curved area of first cone + Curved surface area of second cone

= 2(Surface area of cone)

[since, both cones are identical]

Now, As we know,

Surface area of cone = πrl,

where r = radius and l = slant height

Total Surface area of shape so formed = 2πrl

Given,

Radius, r = 8 cm

Height, h = 15 cm

So,

Area = 2(3.14)(8)(15) = 753.6 cm²