cho 2 goc ke bu aobva boc. biet boc=5aob . khi do goc doi dinh voi boc co so do bang
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{a}{b}=\frac{c}{d}\Rightarrow\frac{c}{a}=\frac{d}{b}=\frac{c-d}{a-b}\)
=> \(\frac{c}{a}=\frac{c-d}{a-b}\) Nhân cả hai vế với \(\frac{a}{c}\Rightarrow\frac{c}{a}.\frac{a}{c}=\frac{a\left(c-d\right)}{c\left(a-b\right)}=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
+ Ta có
\(k=\frac{a}{b}=\frac{b}{c}=\frac{c}{d}=\frac{a+b+c}{b+c+d}=k\Rightarrow\left(\frac{a+b+c}{b+c+d}\right)^3=k^3\) (1)
+ Ta có
\(k=\frac{a}{b}=\frac{b}{c}=\frac{c}{d}\Rightarrow\left(\frac{a}{b}\right)^3=\left(\frac{b}{c}\right)^3=\left(\frac{c}{d}\right)^3=k^3\)
=> \(k^3=\frac{a^3}{b^3}=\frac{b^3}{c^3}=\frac{c^3}{d^3}=\frac{a^3+b^3+c^3}{b^3+c^3+d^3}\) (2)
=> \(\left(\frac{a+b+c}{b+c+d}\right)^3.\left(\frac{a^3+b^3+c^3}{b^3+c^3+d^3}\right)=k^3.k^3=k^6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
aob+boc=180
=>aob+5aob=180
=>aob(1+5)=180
=>6.aob=180
=>aob=180/6=30
=>boc=5.30=150
vay goc doi dinh voi boc=150 do