Question

8.Find total surface area of cone with height 21 m and base diameter 28 m​

Answer 1

Answer:

1726.56m2

Explanation:

l=√r2+h2

l=√14x14+21x21

l=√196+441

l=√632

l=25.24

tsa=πr(l+r)

=22/7x14(25.24+14)

=44x39.24

=1726.56m2

Answer 2

Answer:

2156 cm²

Explanation:

total surface area of a cone=πr(s+r)

where, radius is r, slant height is s.

since, diameter=28, then radius=14

s²=r²+h²

s=

$\sqrt{ {14}^{2} + {21}^{2} }$

s=14+21

s=35

now,

area of cone=22/7×14(35+14)

=22×2×49

=22×98

=2156 cm²