Ta có 

B

H

⊥

 

A

C

BH⊥ AC nên 

Δ

A

B

H

ΔABH vuông tại 

H

H.

 

Mà 

B

A

H

^

=

4

5

∘

BAH

 =45 

∘

  nên 

A

B

H

′

^

 

=

4

5

∘

ABH 

′

 

  =45 

∘

 .

 

Mặt khác 

A

B

D

^

 

=

A

C

D

^

ABD

  = 

ACD

  (góc nội tiếp cùng chắn cung 

A

D

AD) nên 

A

C

D

^

 

=

4

5

∘

ACD

  =45 

∘

 . (1)

 

C

K

 

⊥

 

A

B

CK ⊥ AB nên 

Δ

A

C

K

ΔACK vuông tại 

K

K.

 

Mà 

C

A

K

^

 

=

4

5

∘

CAK

  =45 

∘

  nên 

A

C

K

^

 

=

4

5

∘

ACK

  =45 

∘

 . (2)

 

Từ (1) và (2) ta có 

D

C

E

^

 

=

9

0

∘

DCE

  =90 

∘

  nên 

D

E

DE là đường kính.

 

Vậy 

D

D, 

O

O, 

E

E thẳng hàng.

     My Dream House

My dream house is a modern villa located on a peaceful hillside with stunning views of nature. It will have a sleek, contemporary design with large glass windows, a spacious balcony, and a beautiful garden surrounding it. Inside, there will be a cozy living room, a modern kitchen, four comfortable bedrooms, and a study room filled with books. The house will also have a swimming pool, a home theater, and a rooftop terrace. I will decorate it with minimalist furniture, warm lighting, and artworks to create a relaxing and elegant atmosphere. Plants, colorful rugs, and soft cushions will add charm and comfort, making it the perfect place to live and unwind. And you ?