Jawab no 1 dan 7 dengan pembahasan ya..(1 di kiri, 7 di kanan)

1) U5/U2 = 162/6
(ar^4)/(ar) = 27
r^3 = 3^3
r = 3
ar = 6 => a(3) = 6 => a = 2
S6 = a(r^6 - 1)/(r - 1) = 2(3^6 - 1)/(3 - 1) = 2(729 - 1)/2 = 728

7) A + B + C = 180° => 105° + B + 45° = 180° => B = 30°
AC/(sin B) = AB/(sin C)
AC/(sin 30°) = 10/(sin 45°)
AC/(1/2) = 10/(1/2 √2)
AC/1 = 10/√2
AC = 10/√2 . √2/√2 = (10√2)/2 = 5√2