a: Xét tứ giác AEHF có

\(\widehat{AEH}+\widehat{AFH}=180^0\)

Do đó: AEHF là tứ giác nội tiếp

b: Xét ΔADC vuông tại D và ΔAEH vuông tại E có 

\(\widehat{EAH}\) chung

DO đó: ΔADC\(\sim\)ΔAEH

Suy ra: AD/AE=AC/AH

hay \(AD\cdot AH=AE\cdot AC\)

Bài 1.5 bạn nhé!

1.6 đây bạn nhé!

1.8)

a)Áp dụng hệ thức lượng trong tam giác vuông vào ΔABC vuông tại A có AD là đường cao ứng với cạnh huyền BC, ta được:

\(\left\{{}\begin{matrix}AB^2=BH\cdot BC\\AC^2=CH\cdot BC\end{matrix}\right.\)

\(\Leftrightarrow\dfrac{AB^2}{AC^2}=\dfrac{BH\cdot BC}{CH\cdot BC}=\dfrac{BH}{CH}\)(đpcm)

1 Because she went to bed late last night, she couldn't go to school on time

2 It rained heavily so we couldn't go to the theater

3 The wind was strong, so the tree in my garden was uprooted

4 He fell asleep while driving, so he had an accident

5 If I had a guitar here, I could sing you a song

6 If I didn't need to finish my assignment, I could help you with your homework

7 If you don't study hard, you may fail the exam

8 If there is no oil in the engine, the car will breakdown

9 If it hadn't been for your help, I couldn't have finished the report

10 If it hadn't been for her disapprova, he would have been given that job

11 The house seemed as if it had been occupied for years

Bạn nào làm giúp mk thì mk sẽ tick cho nha☺️

a: Ta có: \(K=\left(\dfrac{2+x}{2-x}+\dfrac{x}{2+x}-\dfrac{4x^2+2x+4}{x^2-4}\right):\left(\dfrac{x^2+9}{x^2-2x}-\dfrac{2x}{x-2}\right)\)

\(=\dfrac{-x^2-4x-4+x^2-2x-4x^2-2x-4}{\left(x-2\right)\left(x+2\right)}:\dfrac{x^2+9-2x^2}{x\left(x-2\right)}\)

\(=\dfrac{-4x^2-8x-8}{\left(x-2\right)\left(x+2\right)}\cdot\dfrac{x\left(x-2\right)}{-x^2+9}\)

\(=\dfrac{-4\left(x^2+2x+1\right)}{x+2}\cdot\dfrac{x}{-\left(x-3\right)\left(x+3\right)}\)

\(=\dfrac{-4x\left(x+1\right)^2}{-\left(x-3\right)\left(x+3\right)\left(x+2\right)}\)

                                         Sau khi giặt , mỗi 1m vải theo chiều dài sẽ còn lại :

                                                   15/16.17/18.8/10=17/24 (m²) vải

                           => Phải mua 24m để sau khi giặt có 17m² vải

câu tra loi cua Quy Nha Thiên giong trong sach giai, ma sach giai chi ghi co nhieu do thoi.                                                                        vay ban tim o dau ma co dc 15/16, 17/18 va 8/10 dzi. van de chinh la phai tim dc nhg phan so do bang cach nao da. lop mk cung dg dau voi bai nay ne.