tolong bantu sama caranya ya plisssss

No. 1
a) K = KN+NM+LM+KL
=>KN = LM ; KL = NM
=>K = 2KN+2KL = 2×(16+28) = 2×44 = 88cm

No. 2
Dik:
L = 120cm2
a = 15cm
Dit: t = ?
Jwb:
L = a×t <=> t = L/a
=========> t = 120cm2 / 15cm = 8cm

No. 3
Dik:
L = 90cm2
t = 15cm
Dit: a = ?
Jwb: a = L/t => a = 90cm2 / 15cm = 6cm

No. 4
a) Keliling = 10+10+17+15+6+10 = 68cm
b) Luas = 1/2 (a+b)(t)
=======> 1/2 (32+8)(16) = 1/2×40×16 = 320cm2

No. 5
Dik:
* a : b = 2 : 5 <=> Misal: a = 2n dan b = 5n
* c (panjang kaki) = 10cm
* t = 8cm
* L = 80cm2
Dit:
a) a = ?
b) b = ?
c) K = ?
Jwb:
a) Luas = 80cm2 = 1/2(a+b)×t
=> 80cm2 = 1/2(2n+5n)×8cm = 1/2×7n×8cm
=> 80cm2 = 7n×4cm => 20cm = 7n
=> n = (20/7)cm = 2. 6/7 cm
Maka, a = 2n = 2×20/7 = (40/7) cm = 5. 5/7cm
b) b = 5n = 5×20/7 = (100/7)cm = 14. 2/7cm
c) K = a+b+2c = 40/7 + 100/7 + 2×10
=> K = 140/7 + 20 = 20 + 20 = 40cm

No. 6 (itu kayaknya salah letak angka ya... harusnya 14 cm-nya di PS bukan PQ)
Dik:
* PS = a = 14cm
* QR = b = 9cm
* L = 138cm2
Dit: SR = ?
Jwb:
=> L = 1/2 × (9+14) × t
=> 138 = 1/2 × 23t
=> 138×2 = 23t
=> 276 = 23t => t = 276/23 = 12cm = PQ

=> SR = akar {(SP-RQ)^2 + PQ^2}
=> SR = akar {(14-9)^2 + 12^2}
=> SR = akar (5^2 + 12^2)
=> SR = akar (25 + 144) = akar (169)
=> SR = 13cm

Semoga membantu^^