x=\(\frac{\int_l^{ }x\ dl}{\int_{l\ }^{ }dl}=\int_{\frac{-\Pi}{2}}^{\frac{\Pi}{2}}r\ \cos\theta\ r\theta\)
x= r cos θ
dl= r d θ
\(\frac{r\ sen\ \theta\left|\frac{\frac{\Pi}{2}}{\frac{-\Pi}{2}}\right|}{\theta\left|\frac{\frac{\Pi}{2}}{\frac{-\Pi}{2}}\right|}=\frac{r\left[1+1\right]}{\Pi}=\frac{2\left(2\right)}{\Pi}=\frac{4}{2}=1.25\)
\(\left(1\right)\ \Sigma\ fx\) Bx= 1lb
2.- Σ fy Ax= 1lb
3.- Σ ma Ay= \(\Pi\) lb
1.- Ax +Bx
2.- Ay -w= 0
Ay= w
3.- -xw +Bx (4ft)= 0
-2 r/\(\Pi\) ( 0.5 lb/ft)\(\Pi\) + Bx (4ft) =0
-2\(r^2\)(0.5 lb/ ft) + 4 ft Bx= 0
4ft Bx= 2 \(r^2\) ( 0.5 lb/ft)
Bx= \(2r^2\)/4 ft (0.5 lb/ ft) =[ 2(4ft) / (4ft) ] (0.5 lb) = 1 lb