Taman berbentuk trapesium sama kaki dengan panjang sisi sejajar ( x + 4 )m dan ( 3x + 2 )m. Jika jarak kedua garis sejajar 2x m dan luasnya 180 m². Kelilingnya

Luas = 180
1/2 × (x+4 + 3x+2) × 2x = 180
(4x + 6)× 2x = 180×2
(4x + 6) × 2x = 360
(4x + 6) × x = 360/2
(4x + 6) × x = 180
(4x + 6) × x = 30 × 6

4x + 6 = 30
4x = 30-6
4x = 24
x = 24/4
x = 6

x = 6

sisi sejajar=>
x+4 = 6+4 = 10 cm dan
3x+2 = 3×6 + 2 = 18+2 = 20 cm

tinggi = 2x = 2×6 = 12 cm

sisi miring/kaki trapesium= akar(12^2 + ((20-10)/2)^2) = akar(12^2 + 5^2) = akar(144+25) = akar169 = 13 cm

Keliling= 2×13 + 10 + 20 = 26 + 30 = 56 cm