keliling trapesium abcd adlah....cm mohon pake cara ya.thanks

c² = a² + b²
c² = 21² + 20²
c² = 441 + 400
c² = 841
c = √841
c = 29 cm

K = a + b + c + d
K = 20 + 20 + 29 + 41
K = 40 + 70
K = 110 cm