Tolong no 15-19 sama cara ya :-)

SEMOGA MEMBANTUU YAAAA

15.
Keliling = semua sisi ditambah
40 = x + 5 + x + 7 + 8
40 = 2x + 20
40 -20 = 2x
20 = 2x
10 = x
Alas = 8 cm
Tinggi = x + 5
= 10 + 5
= 15 cm
Luas = alas x tinggi/2
= 8 x 15/2
= 60
Jawaban : C. 60 cm2

16.
Alas = 9 + 5
= 14cm
Tinggi = 12cm
Luas = 14 x 12/2
= 84cm2
Jawaban : B.84cm2

17.
(i) 3 + 4 = 5 (pangkat 2)
9 + 16 = 25 (Benar)
(ii) 1 + 2 = 3 (pangkat 2)
1 + 4 = 9 (salah)
(iii) 5 + 3 = 7 (pangkat 2)
25 + 9 = 49(salah)
(iv) 2 + 5 = 8(pangkat 2)
4 + 25 = 64(salah)
so, yg benar hanya (i)

18.
C = B - A
C = 98 - 35
C = 63
Jawaban : C.63°

19.
R = Q = 180 - 100
= 80°
P = 180 - 80 - 80 = 20°
Jawaban : D. 20°