Bantu kaleeeee!! luas permukaan kerucut yang mempunyai luas alas 78.5 cm^2 dan tinggi 12 cm dengan n=3.14 adalah . . . cm^2 ??
ariefpriambudi
La=78,5cm^2 3,14xr^2=78,5cm^2 r^2=25cm^2 r=5cm s^2=12^2+5^2=144+25=169 s=13cm l permukaan=l alas+l sel l per=78,5+(3,14x5x13)=78,5+204,1=282,6cm^2
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israan
Mencari r terlebih dahulu. L = 78,5 = 3,14 . r2 r2 = 78.5 ÷ 3.14 r2 = 25 r = √25 r = 5 Lalu Lp= =3,14 . 5 (5+13) =3,14 . 5 . 18 =282,6 cm2
3,14xr^2=78,5cm^2
r^2=25cm^2
r=5cm
s^2=12^2+5^2=144+25=169
s=13cm
l permukaan=l alas+l sel
l per=78,5+(3,14x5x13)=78,5+204,1=282,6cm^2
L =
78,5 = 3,14 . r2
r2 = 78.5 ÷ 3.14
r2 = 25
r = √25
r = 5
Lalu
Lp=
=3,14 . 5 (5+13)
=3,14 . 5 . 18
=282,6 cm2