tolong jawab yh pertanyaan nomor 7 tolong pake cara

maaf kalau salah
semoga membantu :)

FB=29^-21^
=√841-441
=√400
=20cm
EF=50-FB
=50-20
=30
L=(a+b)*t/2
=(30+70)*21/2
=2100/2
=1050 cm