... + S 4 = 423 +60+3 42+ 241,5 =1066,5 mm 2 18.47 = 423 mm 2 2 8.15 = 60 mm 2 2 (15 +23 ).18 = 3 42 mm 2 2 21 .23 = 24 1,5 mm 2 2 Baøi 37/ (130) 47 mm 18 8 15 18 21 23 S 1 = S 2 = S 3 = S 4 = 120 m 150m ... mm 2 ) Vaọy :S ẹAM ẹAT = 445,5 . 5000 2 = 11 137 500 000 mm 2 = 11 137,5( m 2 ) Baứi 39/ (131) )(5,370 2 13) .25 32( 2 ).( 2 mm HCCEAB = + = + )(75 2 6 .25 2 . 2 mm DKCE == S 1 = 42 cm 2 S 2 = 2cm ... S = a.b a.b 2 a 2 a.h 2 (a+b).h 2 a.h d1.d2 2 KIEÅM TRA BAØI CUÕ: a h a h h a b d 1 d 2 S 1 S 2 S 3 S ña giaùc = S 1 + S 2 + S 3 S 2 S 3 S 1 S 2 S 3 S 1 S AMNPQ = S ABC –(S 1 + S 2 ) B C A N...