Animated Solution for Mathematics - Straight Lines: The incentre of the triangle with vertices (1,3),(0,0) and (2,0) is
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Visualized Solution
Plotting the Base Vertices
Let's visualize the given vertices on the Cartesian plane.
B(0,0) is at the origin.
C(2,0) lies on the positive x-axis.
Completing the Triangle
The third vertex is A(1,3).
Connect the vertices to form △ABC.
Calculating Side Length AB
Distance formula: d=(x2−x1)2+(y2−y1)2
AB=(1−0)2+(3−0)2
AB=1+3=2
Calculating Sides BC and CA
BC=(2−0)2+(0−0)2=2
CA=(2−1)2+(0−3)2=1+3=2
Identifying the Triangle Type
We observe that AB=BC=CA=2.
Since all three sides are equal in length, △ABC is an equilateral triangle.
The Equilateral Shortcut
General Incentre formula: I=(a+b+cax1+bx2+cx3,a+b+cay1+by2+cy3)
In an equilateral triangle, all centers (Centroid, Incentre, Circumcentre, Orthocentre) coincide.
Therefore, Incentre = Centroid.
Applying the Centroid Formula
Centroid G(x,y)=(3x1+x2+x3,3y1+y2+y3)
We will substitute the coordinates of A(1,3), B(0,0), and C(2,0).
Computing the x-coordinate
x=31+0+2
x=33=1
Computing the y-coordinate
y=33+0+0
y=33=31
Final Answer and Visualization
The Incentre is I(1,31).
Key Takeaway: Always check if a triangle is equilateral or right-angled before applying complex coordinate geometry formulas.
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The Sigma Insight: Centroid, Incenter, Orthocenter, and Circumcenter
Solution Diagram
Analyzing the Geometry
Welcome, future engineer. Today, we are going to solve a problem that seems like a standard coordinate geometry exercise but is actually a profound lesson in observation.
We are given three vertices: A(1,3), B(0,0), and C(2,0). When you see these coordinates, don't just jump into the formula. Stop, breathe, and visualize.
Plotting these points on the Cartesian plane reveals a beautiful, symmetric structure. Point B is at the origin, and C sits on the x-axis. Point A is perched above, creating a triangle.
Calculating Side Lengths
Now, let's calculate the side lengths. Using the distance formula d=(x2−x1)2+(y2−y1)2, we find the lengths of the sides:
AB=(1−0)2+(3−0)2=1+3=2
BC=(2−0)2+(0−0)2=2
CA=(2−1)2+(0−3)2=1+3=2
This is the 'Aha!' moment. All sides are equal, confirming that we have an equilateral triangle.
The Master Equation
In the world of geometry, symmetry is a gift. For an equilateral triangle, the incentre, centroid, circumcentre, and orthocentre all collapse into a single point.
This means we don't need the complex incentre formula. We can simply find the centroid, which is the average of the coordinates:
G=(3x1+x2+x3,3y1+y2+y3)
Plugging in our values, we calculate the coordinates:
x=31+0+2=1
y=33+0+0=33=31
Final Result
Our incentre is located at the point:
(1,31)
This problem teaches us that the most efficient path is often found by observing the properties of the figure before applying the formulas. Keep this mindset, and you will conquer the JEE.