The points where the 2 graphs intersect is where x = 0 and x = 2.
- 2 2
x = INT x dA / INT dA
0 0
INT dA = INT -x^2 + 4x + 3 - (x^2 + 3 ) dx = INT -2x^2 + 4x
= -2 x^3/3 + 2x^2
= 2.667 between 0 and 2
xdA = -2x^3 + 4x^2 INT xdA = -x^4/2 + 4x^3/3 = 2.667
centroid = 2.667 / 2.667 = 1 (x = 1)
The answer is given above
We have the triangle 30° - 60° - 90°.
The lenght of the sides are in proportion: 

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