a) 25

b) -5

c)1

a)

_ Xét \(\Delta\) AKC và \(\Delta\) AHI có :

+ góc AKC = gócÂHB = 90^o

⁺ A là góc chung

+ AB = AC ( gt )

=> \(\Delta\)AHB = \(\Delta\) AKC ( g.c.g)

=> AH = AK ( đpcm )

b)

_ Xét \(\Delta\) AKI và \(\Delta\) AHI có

+ góc AKI = góc AHI = 90⁰

+ AH = AK ( c/m trên )

+ AI là cạnh chung

=> \(\Delta\) AKI = \(\Delta\) AHI ( cạnh huyền - cạnh góc vuông )

=> góc KAI = gócHAI ( 2 góc tương ứng )

c)

_ Xét \(\Delta\) ABD và \(\Delta\) ACD có :

+ AB = AC ( gt )

+ AD chung

+ góc ADB = góc ACD = 90^o

=> \(\Delta\)ABD = \(\Delta\) ACD ( cạnh huyền - cạnh góc vuông )

=> AI \(\perp\) BC

Còn lại k biết lm

Today , I interviewed my classmates about theỉ favorite actor . Every one has diffirent opinions . Ha , Anh , Trinh like actress Bao Thanh , Minh Hang , Nha Phuong . Minh Duc , Ha Anh , Ngoc Anh like actor Toki , K.O , Tung Maru They are nember of Uni5 musicgroup . My classmate are like young actor . Half of people have interviewed,the favorite actors are young and practiced . My classmates don't like foreign actor . It is result of my interview.