tolong kerjain dong semua besok dikumpulkan makasih

1. a.) BC = 9cm
b.) 7x+6 = 5x+8
7x-5x = 8-6
2x = 2
x = 1
c.) AB = 7x+6 cm
AB = 7(1)+6
AB = 7+6
AB = 13 cm

3. Belah ketupat KLMN
4 x s = 60
s = 60 : 4
s = 15
KM = ?
OK² = KL² - LO²
OK² = 15² - 9²
OK² = 225 - 81
OK² = 144
OK = √144
OK = 12
KM = 2 x 12 = 24cm
L = 1/2 x d1 x d2
= 1/2 x KM x LN
= 1/2 x 24 x 18
= 216
Jadi, luas = 216 cm.

4. OA = 16
BD = L = 1/2 x d1 x d2
300 = 1/2 x 25 x d2
d2 = 300 : 2 x 25
d2 = 6cm
BD = 6cm
DC = BC = 9² + 3²
= 81 + 9
= 90
= √90
= 3√10
Maaf, cuma bisa yang ini