Perhatikan gambar berikut. luas permukaan kerucut diatas adalah?

Jawaban:

Diketahui:

jari jari (r) = 9 cm

tinggi (t) = 12 cm

Ditanyakan:

Luas permukaan kerucut = … ?

Penyelesaian:

cari panjang sisi selimut kerucut menggunakan rumus phytagoras

begin{gathered} {s}^{2} = {r}^{2} + {t}^{2} \ {s}^{2} = {9}^{2} + {12}^{2} \ {s}^{2} = 81 + 144 \ {s}^{2} = 225 \ s = 15 : cmend{gathered}

s

2

=r

2

+t

2

s

2

=9

2

+12

2

s

2

=81+144

s

2

=225

s=15cm

Luas permukaan kerucut

begin{gathered} = pi times r(r + s) \ = 3.14 times 9(9 + 15) \ = 28.26 times 24 \ = 678.24 : {cm}^{2} end{gathered}

=π×r(r+s)

=3.14×9(9+15)

=28.26×24

=678.24cm

2