Геометрия 8 класс

Question

Помогите решить первые 4 задания

sergei_iankov_3 · Accepted Answer

AD = 5 + AB
2(AD + AB) = 22
2(5 + AB + AB) = 22
10 + 4AB = 22
4AB = 12
AB = 3
AD = 8
S = AD*AB = 24
Ответ: 24 см^2
AD = 2AB 
2(AD + AB) = 18
2(2AB + AB) = 18 
6AB = 18  
AB = 3 
AD = 6 
S = AD*AB = 18 
Ответ: 18 см^2
S = BD*AD = 1800
CD = AB = 60
S = BK*CD
1800 = 60BK
BK = 30
Ответ: 30
S = BC*DH
72 = 6BC
BC = 12
P = 2(BC + DC) = 2(12+8) = 40
Ответ: 40 см.

natusha_1 · Answer

1)  P =22,   AB= 3, AD = 8  
  S = 3* 8 = 24
2)  P = 18 ,   AB = 3, AD = 6
S =  3 * 6 = 18
3)  S = 36* 50 = BK * 60
BK = 1800 : 60 = 30
4) 72 = BC * 6, BC = 12
P = 2*(12+8) = 40