Question

if the radius and slant height of a cone are r/2 and 21 then finds its total surface area ???

Answer 1

slant height =21
radius=r/2
TSA = pie r(l +r)
= 22/7× r/2 (21+r/2)
=22/7×r/2×(42+r)/2
= 11/4×(42r +r^2)
= 11/4(r^2+42r)
=11/4×r(r +42)