Object is a regular pentagon(5 equal sides) with a missing triangular piece. Call the length of a side a. The missing piece is one of the five triangles that are formed by drawing lines from the verticies to the center.
-
A little trig will show that:
Area of entire pentagon K = 1.72048*a²
Area of 1 triangle k = .3441*a²
Y value of CM of bottom triangle y = -.4588*a
Ycm = ΣM/ΣA = [K*0 - k*y]/[K - k]
Substituting from above,
Y cm = +0.1147*a
Area of entire pentagon K = 1.72048*a²
Area of 1 triangle k = .3441*a²
Y value of CM of bottom triangle y = -.4588*a
Ycm = ΣM/ΣA = [K*0 - k*y]/[K - k]
Substituting from above,
Y cm = +0.1147*a