kalo ngerti jawab y..

3.
keliling = 100 cm

seginya gak jelas, segitiga, segiempat, segilima?

asumsi segiempat
2P + 2L = 100
P + L = 50
P = 50 - L

Luas = P x L = (50 - L) x L = 50L - L²

4.
a. 14 x 8 = 112
b. 1/2 x 8 x 6 = 24
c. 1/2 x (24+16) x (12+12) = 1/2 x  40 x 24 = 480
d. 1/2 x (5+14+5+14) x 12 = 228

5.
keliling = 12 x 4 = 48
luas arsir = (12x12) - (8x8) = 80