Question

Sebuah kerucut punya luas alas 616 cm kuadrat. Tinggi 48 cm. Luas permukaan ?

Answer 1

Luas alas kerucut = πr²
                     616 = 22/7 x r²
                        r² = 616 : 22/7
                       r² = 196
                        r  = √196
                         r = 14cm

s = √t²+r²
   = √48²+14²
   = √2304+196
   = √2500
s = 50 cm

jadi luas permukaan = πr² + π.r.s
                                 = 616 + 22/7 x 14 x 50
                                 = 616 + 2200
                                 = 2816 cm