No 3 dan 4 mohon cepat dan benar. au sekolah ni plisss

3.
BD² = 12² + 9²
BD² = 15
 
keliling BDC = BD +BC + CD = 15 + 7 + 20 = 42 cm
Luas BDC = 1/2 x alas x tinggi = 1/2 x 7 x12 = 42 cm²


4.
a= 20
b = 11
c= √(5²+12²) = 13

Keliling = a+b+c  = 20+11+ 13 = 44 cm²
Luas = 1/2 (alas x tinggiI = 1/2 (11 x 12) = 66 cm²
..

3.
a.
panjang sisi miring
s^2 = 12^2 + 9^2
s^2 = 144 + 81 = 225
s = 15

Keliling = 15 + 7 + 20 = 42 cm

Luas
= 1/2 . (9+7) . 12 - 1/2 . 12 . 9
= 96 - 54
= 42

b. caranya sama. kerjain sendiri ya

4.
Keliling = 10 + 10 + 12 = 32

Tinggi
t^2 = 10^2 - 6^2
t^2 = 100 - 36 = 64
t = 8

Luas
= 1/2 × 12 × 8
= 48