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nugyenhan128
6 tháng trước

Tính các góc của tam giác ABC , biết AB = 3cm , AC= 4cm và BC =5 cm

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trongduong2007
6 tháng trước

Đáp án:

 bạn tham khảo 

`text{@Trọng Dương}`

Giải thích các bước giải:

 

trunghieu777
6 tháng trước

Đáp án:

 

Giải thích các bước giải:

Ta có:
`- AB=3⇒AB^2=3^2=9`
`- AC=4⇒AC^2=4^2=16`
`- BC=5⇒BC^2=5^2=25`
`=>  AB^2+AC^2=9+16=25=BC^2`
`=> Δ ABC` vuông tại `A.`
Ta có: `sinB=(AC)/(BC)=45=0,8⇒hat(B)=53^o``8`
`hat(C)=90^o−hat(B)=90^o−53^o``8=36^o``52`

`hat(A)=180^o-36^o``52-53^o``8=90^o`

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