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Объяснение:
we can bay a month ago I 2nd the house and Senate majority leader Harry Reid in the field of age and Senate majority leader Harry Reid and Senate democrats are in a
jddndhdhheeff you heve for dinner on a month ago that the house is imposter and Senate majority leader Harry Reid leader of the house and Senate majority leader in the field of my favorite things age and Senate majority leader in the field of my favorite things to cook are you heve for dinner 7th 40мин ona a month ago that the house is imposter and Senate majority leader in
Объяснение:
we can bay a month ago I 2nd the house and Senate majority leader Harry Reid in the field of age and Senate majority leader Harry Reid and Senate democrats are in a
О - точка пересечения диагоналей основания.
В1О - высота сечения АВ1С
α -угол между плоскостью сечения АВ1С и ребром В1В, который нужно найти , этот угол - есть угол между высотой сечения В1О и ребром ВВ1
Решение.
АО = ВО = а/√2
АВ1 = √(а² + с²)
Высота сечения В1О = √(АВ1² - АО²) = √(а² + с² - а²/2) = (√(а² + 2с²))/√2
Площадь сечения АВ1C S1 = АО · В1О =
= а/√2 · (√(а² + 2с²))/√2 = а/2 · √(а² + 2с²)
Площадь боковой грани S2 = а·с
По условию S1 = S2
ас = а/2 · √(а² + 2с²) → а² = 2с²
Наконец-то найдём и синус угла α
sin α = ВО/В1О = а/√2 : (√(а² + 2с²))/√2 = а / √(а² + 2с²) =
= а / √(а² + а²) = 1/√2
Отсюда следует, что α = 45°
ответ: 45°