Gọi h là đường cao của hình thoi ACC'A' ứng với cạnh AC

vì mặt ACC'A' vuông với đáy nên h cũng vuông góc với đáy

nên h là đường cao của lăng trụ

ta có :\(h\times AC=8a^2\Leftrightarrow h=\frac{8a^2}{\sqrt{AB^2+AC^2}}=4a\)

thể tích lăng trụ là : \(a\times a\sqrt{3}\times4a=4\sqrt{3}a^3\)

ta có \(S_{đáy}=\left(3a\right)^2sin30^0=\frac{9a^2}{2}\)

đường cao là :\(a\sqrt{6}\times sin60^0=\frac{3\sqrt{2}}{2}a\)

Vậy thể tích lăng trụ là : \(\frac{9}{2}a^2\times\frac{3\sqrt{2}}{2}a=\frac{27\sqrt{2}a^3}{4}\)

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đang FA hết

Poverty is no shame

My parents died in a traffic accident when I was ten years old, so I grew up with my grandmother who was too old and weak to work. I had to leave school and did odd jobs to earn a living: selling lottery kets, washing dishes and doing babysitting. When I was 15, my grandma encouraged me to attend evening classes, so I could improve my literacy and job prospects.

After lots of hardship and effort, I completed secondary education and passed a challenging exam to enter Medical University, which is the dream of many students. However, I could not pay the tuition fees and had to reject the offer. The door to a new life was closed before me. I was completely disappointed and saw only gloomy days ahead.Then something incredible happened: I was awarded a scholarship from The Thanh Nien for college students from poor families. This was really a turning point in my life because I could start my university studies and hope for a better future.

Six years of hard work at the university and of trying to live on a very tight budget came to an end at last. Now I am working as a doctor at a hospital, but I will never forget those difficult days. I am planning to set up and run a charitable organisation to help poor students, as a way to acknowledge other people for supporting me.

I've told my own story hoping to encourage other people me to overcome hard times. Don't let poverty defeat you and destroy your hopes for a better future. This is my motto.