1. ## statics lamina

im stuck on question 6
i am having trouble finding the centroid of the triangle. i plan on getting forces up=forces down and then taking my moments. i heard you have to take moments twice for the question. i do not know where in should take moments through.

2. ## Re: statics lamina

The coordinates of the "centroid" of a triangle is simply the average of the coordinates of the three vertices. That is, if the coordinates of the three vertices of a triangle are $\displaystyle (x_0, y_0, z_0)$, $\displaystyle (x_1, y_1, z_1)$ and $\displaystyle (x_2, y_2, z_2)$ then the centroid is $\displaystyle \left(\frac{x_0+ x_1+ x_2}{3}, \frac{y_0+ y_1+ y_2}{3}, \frac{z_0+ z_1+ z_2}{3}\right)$.

3. ## Re: statics lamina

Thanks
Once I let forces equal up and down do you know what I do next?

4. ## Re: statics lamina

so i have got 3 equations 4w/3 +w=t1+t2+t3 from forces up=down. taking moments through Q 5(t1)+4(t3)=√5(4w/3)+√ 13/3(w)
taking moments through R 4t2+3t1=√5(4w/3)+5/3 (w)
i cant solve these though