Math Forum :: View topic – 求BC和 S△ABC.

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Hilda

Joined: 15 Apr 2004Posts: 12

Posted: Thu Apr 15, 2004 10:46 pm    Post subject: 求BC和 S△ABC.

在△ABC中,AB=2√3,∠A=45°,∠B=60°,求BC和 S△ABC.

me

Frequent VisitorJoined: 12 Feb 2004Posts: 213

Location: Hong Kong

Posted: Thu Apr 15, 2004 11:27 pm    Post subject: Re: 求BC和 S△ABC.

Hilda wrote:

在△ABC中,AB=2√3,∠A=45°,∠B=60°,求BC和 S△ABC.

AB/sinC=BC/sinA, so we can find BC. area of ABC=1/2(AB)(BC)sinB, so we can find it.

Another way is to drop a from A or B or C to the opposite side.

Hilda

Joined: 15 Apr 2004Posts: 12

Posted: Fri Apr 16, 2004 10:16 pm    Post subject: Re: 求BC和 S△ABC.

me wrote:

Hilda wrote:

在△ABC中,AB=2√3,∠A=45°,∠B=60°,求BC和 S△ABC.

AB/sinC=BC/sinA, so we can find BC. area of ABC=1/2(AB)(BC)sinB, so we can find it.

Another way is to drop a from A or B or C to the opposite side.

AB/sinC=BC/sinA中的sinC同sinA點求呀?比得AB=2√3一個值咋喎?

Ellen

Frequent VisitorJoined: 28 Oct 2003Posts: 212

Location: CUHK

Posted: Fri Apr 16, 2004 11:24 pm    Post subject:

so
and the easiset way you can find sinC is using a calculator to find [/tex]

Hilda

Joined: 15 Apr 2004Posts: 12

Posted: Fri Apr 16, 2004 11:30 pm    Post subject:

咁點解係AB/sinC=BC/sinA?

Soarer

Frequent VisitorJoined: 18 Jan 2004Posts: 213

Location: Hong Kong

Posted: Fri Apr 16, 2004 11:55 pm    Post subject:

Hilda wrote:

咁點解係AB/sinC=BC/sinA?

請問你幾年級?

Hilda

Joined: 15 Apr 2004Posts: 12

Posted: Fri Apr 16, 2004 11:59 pm    Post subject:

Soarer wrote:

Hilda wrote:

咁點解係AB/sinC=BC/sinA?

請問你幾年級?

中三~咁你呢?

me

Frequent VisitorJoined: 12 Feb 2004Posts: 213

Location: Hong Kong

Posted: Sat Apr 17, 2004 2:12 am    Post subject:

Hilda wrote:

Soarer wrote:

Hilda wrote:

咁點解係AB/sinC=BC/sinA?

請問你幾年級?

中三~咁你呢?

Soarer is f.5.

newb1e

Joined: 05 Apr 2004Posts: 11

Hilda

Joined: 15 Apr 2004Posts: 12

Posted: Sat Apr 17, 2004 2:17 pm    Post subject:

唔該晒以上解答過我問題既人!!!

All times are GMT + 8 Hours

 

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