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Through the centroid of an equilateral t...

Through the centroid of an equilateral triangle, a line parallel to the base is drawn. On this line, an arbitrary point P is taken inside the triangle. Let h denote the perpendicular distance of P from the base of the triangle. Let `h_(1) and h_(2)` be the perpendicular distance of P from the other two sides of the triangle . Then :

A

`h=(h_(1)+h_(2))/(2)`

B

`h=sqrt(h_(1)h_(2))`

C

`h=(2h_(1)h_(2))/(h_(1)+h_(2))`

D

`h=((h_(1)+h_(2))sqrt(3))/(4)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will follow these steps: ### Step 1: Understand the Setup We have an equilateral triangle \( ABC \) with centroid \( G \). A line parallel to the base \( BC \) is drawn through \( G \), and an arbitrary point \( P \) is taken on this line inside the triangle. The distances from point \( P \) to the sides of the triangle are denoted as follows: - \( h \): perpendicular distance from \( P \) to base \( BC \) - \( h_1 \): perpendicular distance from \( P \) to side \( AC \) - \( h_2 \): perpendicular distance from \( P \) to side \( AB \) ### Step 2: Area Relationships The area of triangle \( BPC \) can be expressed in terms of \( h \): \[ \text{Area of } \triangle BPC = \frac{1}{2} \times BC \times h \] Since \( ABC \) is equilateral, let \( BC = a \). Therefore, \[ \text{Area of } \triangle BPC = \frac{1}{2} \times a \times h \] ### Step 3: Area of Triangle \( ABC \) The area of triangle \( ABC \) can be calculated as: \[ \text{Area of } \triangle ABC = \frac{\sqrt{3}}{4} a^2 \] ### Step 4: Area of Triangle \( BGC \) The area of triangle \( BGC \) is one-third of the area of triangle \( ABC \) because \( G \) is the centroid: \[ \text{Area of } \triangle BGC = \frac{1}{3} \times \text{Area of } \triangle ABC = \frac{1}{3} \times \frac{\sqrt{3}}{4} a^2 \] ### Step 5: Relating Areas Since the area of triangle \( BPC \) is equal to the area of triangle \( BGC \): \[ \frac{1}{2} \times a \times h = \frac{1}{3} \times \frac{\sqrt{3}}{4} a^2 \] ### Step 6: Simplifying the Equation Cancel \( a \) from both sides (assuming \( a \neq 0 \)): \[ \frac{1}{2} h = \frac{\sqrt{3}}{12} a \] Multiply both sides by 2: \[ h = \frac{\sqrt{3}}{6} a \] ### Step 7: Area of Triangles \( APB \) and \( APC \) The areas of triangles \( APB \) and \( APC \) can be expressed as: \[ \text{Area of } \triangle APB = \frac{1}{2} \times AB \times h_1 = \frac{1}{2} a h_1 \] \[ \text{Area of } \triangle APC = \frac{1}{2} \times AC \times h_2 = \frac{1}{2} a h_2 \] ### Step 8: Total Area of Triangle \( ABC \) The total area of triangle \( ABC \) can also be expressed as: \[ \text{Area of } \triangle ABC = \text{Area of } \triangle APB + \text{Area of } \triangle APC + \text{Area of } \triangle BPC \] Substituting the areas we found: \[ \frac{\sqrt{3}}{4} a^2 = \frac{1}{2} a h_1 + \frac{1}{2} a h_2 + \frac{1}{2} a h \] ### Step 9: Rearranging the Equation Factoring out \( \frac{1}{2} a \): \[ \frac{\sqrt{3}}{4} a^2 = \frac{1}{2} a (h_1 + h_2 + h) \] Dividing both sides by \( \frac{1}{2} a \) (assuming \( a \neq 0 \)): \[ \frac{\sqrt{3}}{2} a = h_1 + h_2 + h \] Thus, \[ h = \frac{\sqrt{3}}{2} a - (h_1 + h_2) \] ### Step 10: Final Relationship From the area relationships, we can derive that: \[ h = \frac{h_1 + h_2}{2} \] ### Conclusion The correct relationship is: \[ h = \frac{h_1 + h_2}{2} \]
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