Math Problem Statement

The centroid of $\triangle ABC$ is $G$. Find $BG.$

[asy] unitsize (1 cm);

pair A, B, C, G;

A = (5,0); B = (0,0); C = (0,3); G = (A + B + C)/3;

draw(A--B--C--cycle); draw(A--G); draw(B--G); draw(C--G); draw(rightanglemark(A,B,C,8));

label("$A$", A, SE); label("$B$", B, SW); label("$C$", C, NW); label("$G$", G, NE); label("$3$", (C + G)/2, SW, red); label("$4$", interp(A,G,0.7), SW, red); [/asy]

Solution

We are tasked with finding BGBG, the distance between point BB and the centroid GG of ABC\triangle ABC.

Step 1: Coordinates of Points

The given coordinates of the vertices of the triangle are:

  • A(5,0)A(5, 0)
  • B(0,0)B(0, 0)
  • C(0,3)C(0, 3)

Step 2: Centroid Formula

The centroid GG of a triangle with vertices A(x1,y1)A(x_1, y_1), B(x2,y2)B(x_2, y_2), and C(x3,y3)C(x_3, y_3) is given by the formula: G=(x1+x2+x33,y1+y2+y33)G = \left( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \right) Substituting the coordinates of AA, BB, and CC: G=(5+0+03,0+0+33)=(53,1)G = \left( \frac{5 + 0 + 0}{3}, \frac{0 + 0 + 3}{3} \right) = \left( \frac{5}{3}, 1 \right)

Step 3: Distance Formula

The distance between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is given by: d=(x2x1)2+(y2y1)2d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} Using the coordinates B(0,0)B(0, 0) and G(53,1)G\left(\frac{5}{3}, 1\right), we can calculate BGBG: BG=(530)2+(10)2=(53)2+12BG = \sqrt{\left( \frac{5}{3} - 0 \right)^2 + \left( 1 - 0 \right)^2} = \sqrt{\left( \frac{5}{3} \right)^2 + 1^2} BG=259+1=259+99=349=343BG = \sqrt{\frac{25}{9} + 1} = \sqrt{\frac{25}{9} + \frac{9}{9}} = \sqrt{\frac{34}{9}} = \frac{\sqrt{34}}{3}

Thus, the distance BGBG is 343\frac{\sqrt{34}}{3}.

Would you like further details or have any questions?


Here are 5 related questions:

  1. What is the formula for finding the centroid of a triangle?
  2. How would you calculate the centroid if the triangle had different coordinates?
  3. How does the centroid divide each median in a triangle?
  4. Can you explain why the centroid lies inside the triangle for all triangles?
  5. What is the significance of the centroid in applications like physics (center of mass)?

Tip: The centroid divides each median of a triangle in the ratio 2:1, with the longer segment being closer to the vertex.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Triangles
Centroid
Distance Formula

Formulas

Centroid formula: G = ( (x1 + x2 + x3)/3, (y1 + y2 + y3)/3 )
Distance formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2)

Theorems

The centroid of a triangle divides each median in a 2:1 ratio.
The centroid is the intersection point of the medians of a triangle.

Suitable Grade Level

Grades 9-11