Длина прямоугольника 23 дм а ширина на 8см короче чему равен его периметр

1)230-8=222см-ширина. 2)2*(222+8)=460см=46дм-периметр.

Средняя линия - 5, меньшее основание 4. тогда большее основание = 5*2-4 = 6 см.  один из углов трапеции равен 30 градусов, а продолжения сторон образуют угол в 90 гр. следовательно, другой угол при основании будет равен 60 гр.  там, где боковые стороны пересекаются, будет вершина нового прямоугольного треугольника. его боковая сторона, что лежит против угла в 30 гр, будет равна гипотенузе (т. е. нижнему основанию трапеции) , умноженной на синус противолежащего угла (т. е. 30 гр) .  итак, она равна 6*sin30 = 6* 0.5 = 3.  пусть y - боковая сторона малого треугольника. малый и большой треугольник подобны, поэтому 6: 4 = 3 : y, откуда y = 2.  тогда нужная нам сторона трапеции равна 3-2=1. 

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