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III. Complete the following tag questions.

1. There’s a new cartoon, …………isn't there…………………….?

2. They don’t want to sell their house, ………do they…………………?

3. This machine never works very well,………………does it…………?

4. Your parents should stay in the hotel,………………shouldn't they…………?

5. We can’t go camping today,……………can we…………..?

* Change the sentences into the passive voice.

1.They will build a hydropower station in the North of the country next year.

A hydropower station........................will be built in the North of the country next year..................................................................

2.They sell these chemicals everywhere in my hometown.

These chemicals.....................are sold everywhere in my hometown...............................................................................

3.My children will turn off the lights when going to bed.

The lights ..............................will be turned off by my children when they go to bed............................................................................

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2 phút trước

Đáy BC dài số cm là

$200\times2:25=16\left(cm\right)$

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Áp dụng hệ thức lượng:

@$\dfrac{1}{AH^2}=\dfrac{1}{AB^2}+\dfrac{1}{AC^2}$

$\Leftrightarrow\dfrac{1}{24^2}=\dfrac{1}{30^2}+\dfrac{1}{AC^2}$

$\Leftrightarrow\dfrac{1}{AC^2}=\dfrac{1}{1600}$

$\Leftrightarrow AC=40\left(cm\right)$

@Áp dụng định lý pytago $BC=\sqrt{30^2+40^2}=\sqrt{2500}=50\left(cm\right)$

@$AB^2=BH.BC$

$\Rightarrow BH=\dfrac{30^2}{50}=18\left(cm\right)$

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2 phút trước

pytago$\Rightarrow BH=\sqrt{AB^2-AH^2}=\sqrt{30^2-24^2}=18cm$

$có:AB^2=BH.BC\Leftrightarrow BC=\dfrac{AB^2}{BH}=50cm$

$pytago\Rightarrow AC=\sqrt{BC^2-AB^2}=\sqrt{50^2-30^2}=40cm$

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Xét tam giác ABC vuông tại A, đường cao AH

Theo định lí Pytago tam giác ABH vuông tại H

$BH=\sqrt{AB^2-AH^2}=18cm$

Áp dụng hệ thức $AB^2=BH.BC\Rightarrow BC=\dfrac{AB^2}{BH}=50cm$

Theo định lí Pytago tam giác ABC vuông tại A

$AC=\sqrt{BC^2-AB^2}=40cm$

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