tolong ya NO 18 19,20,21

18.) S tak hingga = 45, a = 15
45 = 15/(1-r)
1 - r = 15/45
1 - r = ⅓
r = 1 - ⅓
r = ⅔
Jawaban A

19.) Lihat gambar
Jawaban C

20.)
cos (30°) x 60 meter
= √3/3 x 60 meter
= 20√3 meter

21.)
6 cm ÷ sin(30°) = AC ÷ sin (45°)
6 cm ÷ 1/2 = AC ÷ √2/2
6 cm x 2/1 = AC x 2/√2
12 cm = AC x 2/√2
AC = 12 cm x √2/2
AC = 6√2 cm

Makasih