Area relations of a parabolic segment

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I request your comment about correctness of a parabolic segment construction as given below:

Area of circumscribed chord tangent triangle ABC

By Archimedes thm the area of triangle made by drawing a parallel to chord was shown to be $\frac34 $th.

In the following the area of circumscribed triangle is shown $\frac32 $ times parabolic segment area.

It is shown that yellow area between parabolic arc and chord is $\frac23$ fraction that of triangle $ABC$ between the chord and tangents at ends of chord.

If $(t_2, t_1)$ are slopes at $ (C,A)$ then for a parabola (unit focal length) parameterized as $ (x,y)= (2t, t^2) $ triangle area $ABC$ works out to

$$ ( t_2-t_1)^3/2 $$

The area is evaluated from a determinant of the triangle vertices:

$$ A(2t_1,t_1^2);\; B(2 t_2,t_2^2);\; C(t_1+t_2,t_1t_2);\;$$

The above is found from equation of tangent of the parabola that intersect at $(A,B,C)$ :

$$ y = xt- t^2\,$$

Note that $(x_C,y_C) $ are AM and HM of corresponding coordinates$(x_A,y_A),(x_B,y_B) $;

Area marked yellow is evaluated by integration considering integrand as difference in ordinates

$$\int_{2t_1}^{2 t_2} \dfrac{x^2}{4}-\left(x\;\dfrac{t_1+t_2}{2}- t_1 t_2\right) \;dx = ( t_2-t_1)^3/3 $$

$$ \dfrac{\; Area_{parabolic \;segment}} {\; Area_{chord\;tangents}} =\dfrac23 $$

Has the above result also been established by Archimedes or others later?

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Related Construction of internal /external triangles

Since the ratio of circumscribed to inscribed triangles is 2.

Since the areas are in ratios $ 1:2,$ T should be midpoint of MB, sharing the same base, heights are also in the same ratio.AM is mid-point of AC.BTM is median of triangle ABC.

Is my construction correct? Please comment on the same.