kak tolong dijawab ya pliss buat yg mau poin

Bab Bangun Datar
Matematika SMP Kelas VIII

a] ∠BCD = 90° + 45° = 135°

b] ∠BCE = 90° - 45° = 45°

c] EB = 20 - 15 = 5 cm

d] karena segitiga siku-siku sama kaki, maka
CE = EB = 5 cm

e] BC = 2√CE = 2√5 cm

f] AC = √(AE² + CE²)
AC = √(15² + 5²)
AC = √(225 + 25)
AC = √250
AC = 5√10

g] BD = √(AD² + AB²)
BD = √(5² + 20²)
BD = √(25 + 400)
BD = 5√17 cm

h] keliling = AB + BC + CD + DA
keliling = 20 + 2√5 + 15 + 5
keliling = (40 + 2√5) cm

i] luas = 1/2 x t x jumlah sisi
luas = 1/2 x 5 x (20 + 15)
luas = 87,5 cm²