Предмет: Геометрия, автор: Mary57

АС-диагональ прямоугольника АВСД. основание перпендикуляра ВК, проведенного к этой диагонали, делит её на части 3 и 9 см. найдите площадь прямоугольника. Плииииииииииз!

Ответы

Автор ответа: nov
0

проведем диагональ ВД которая пересекает диагональ АС в точке О.

Решение:

АК=3см, СК=9см(по условию), значит по св-ву диагоналей прямоугольнка ВО=ОД=АО=ОС=6см, отсюда имеем, что КО=9-6=3см. 

Треугольники КВО и АВК- прямоугольные (т.к. ВК- перпендикуляр по услов.). Треугольник АВК= треугольнику КВО (по двум катетам), следовательно ВО=АВ=6см.

треугольник АВД- прямоугольный (т.к. АВСД-прямоугольник), значит по теореме Пифагора имеем, что АД=корень из (12^2-6^2)= 6корень из 3см. Тогда площадь АВСД=6*6корень из3=36корень из 3(см^2).

Похожие вопросы
Предмет: Английский язык, автор: alken12
Помогите с переводом с английского на русский
Astronomers spot the biggest, strangest black hole collision ever found
The cosmic pile-up produced the first black hole of its kind ever detected—and that’s not the weird part.
More than seven billion years ago, two immense black holes circled each other until they collided and merged, a cataclysm so intense that it sent ripples soaring through the fabric of space-time. In the early morning hours of May 21, 2019, Earth trembled from the vibrations sent off by this distant carnage, cluing in astronomers to the biggest cosmic bang they’d ever detected—and one that defies theoretical expectation.The signal picked up by two observatories—LIGO in the United States and Virgo in Italy— came in the form of gravitational waves: disruptions in space-time that massive cosmic events can set into motion.
This signal—named GW190521—came from a truly monstrous collision. Researchers estimate that two black holes 66 and 85 times more massive than our sun spiraled into each other, uniting to form a black hole 142 times more massive than our sun.The event, announced today in Physical Review Letters, is by far the biggest ever detected via gravitational waves. In a fraction of a second, the merging black holes released roughly eight times more energy than that contained within our sun’s atoms, all in the form of gravitational waves. That amount of energy is like setting off more than a million billion atomic bombs every second for 13.8 billion years, the age of the observable universe.
Caltech astronomer Matthew Graham, who isn’t part of the LIGO or Virgo teams, calls the event “probably the largest explosion we’ve ever known in the universe.”
The black hole merger is causing a lot of scientific excitement, for a few reasons. First, the black hole it produced fills in a perplexing gap in our observations. Until now, researchers had found black holes tens of times more massive than our sun and supermassive black holes millions to billions times more massive than our sun, but never had confirmed one between 100 and 100,000 solar masses. Clocking in at about 142 solar masses, GW190521’s final black hole is the first ever found in this intermediate range.