Soal Uji Kompetensi 5 Matematika Kelas 9 Halaman 310 No 8-11, Bangun Ruang Sisi Lengkung

(2t + r)^2 = (Vr^2 + t^2)^2

4t^2 +2.2t.r+r^2 = r^2 + t^2

4t^2 + 4rt + r^2 = r^2 + t^2

4t^2 -t^2 + 4rt + r^2 - r^2 = 0

3t^2 + 4rt = 0

t(3t+4r) = 0

t = 0 atau 3t + 4r = 0

3t + 4r = 0

4r = -3t

r/t = -3/4