10. Prove that the area of the triangle whose vertices are : (a * t_{1} ^ 2, 2a*t_{1}); (a * t_{2} ^ 2, 2a*t_{2}); (a * t_{3} ^ 2, 2a*t_{3}) is a ^ 2 * (t_{1} - t_{2})(t_{2} - t_{3})(t_{3} - t_{1})​

Answer :

Answer:

To prove the area of the triangle with vertices \( (a \cdot t_1^2, 2a \cdot t_1), (a \cdot t_2^2, 2a \cdot t_2), (a \cdot t_3^2, 2a \cdot t_3) \) is \( a^2 \cdot (t_1 - t_2)(t_2 - t_3)(t_3 - t_1) \), we can use the formula for the area of a triangle formed by three points in a coordinate plane.

The formula for the area of a triangle with vertices \( (x_1, y_1), (x_2, y_2), (x_3, y_3) \) is given by:

\[ \text{Area} = \frac{1}{2} |x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2)| \]

Let's apply this formula to the given vertices:

\[ \text{Area} = \frac{1}{2} |(a \cdot t_1^2)(2a \cdot t_2 - 2a \cdot t_3) + (a \cdot t_2^2)(2a \cdot t_3 - 2a \cdot t_1) + (a \cdot t_3^2)(2a \cdot t_1 - 2a \cdot t_2)| \]

Simplify:

\[ \text{Area} = \frac{1}{2} |2a^2t_1^2(t_2 - t_3) + 2a^2t_2^2(t_3 - t_1) + 2a^2t_3^2(t_1 - t_2)| \]

\[ = \frac{1}{2} |2a^2(t_1^2(t_2 - t_3) + t_2^2(t_3 - t_1) + t_3^2(t_1 - t_2))| \]

\[ = \frac{1}{2} |2a^2(t_1^2t_2 - t_1^2t_3 + t_2^2t_3 - t_2^2t_1 + t_3^2t_1 - t_3^2t_2)| \]

\[ = \frac{1}{2} |2a^2(t_1t_2(t_1 - t_2) + t_2t_3(t_2 - t_3) + t_3t_1(t_3 - t_1))| \]

\[ = |a^2(t_1 - t_2)(t_2 - t_3)(t_3 - t_1)| \]

\[ = a^2 \cdot |(t_1 - t_2)(t_2 - t_3)(t_3 - t_1)| \]

\[ = a^2 \cdot (t_1 - t_2)(t_2 - t_3)(t_3 - t_1) \]

Therefore, we have proved that the area of the triangle with vertices \( (a \cdot t_1^2, 2a \cdot t_1), (a \cdot t_2^2, 2a \cdot t_2), (a \cdot t_3^2, 2a \cdot t_3) \) is \( a^2 \cdot (t_1 - t_2)(t_2 - t_3)(t_3 - t_1) \).

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