Math Problem Statement

What are the coordinates of point B on line AC such that AB is 3 times as long as BC?

Solution

The problem involves finding the coordinates of point BB on line segment AC\overline{AC} such that ABAB is 3 times as long as BCBC. Let's solve this step-by-step using the coordinates of points AA and CC given in the graph.

Step 1: Identify coordinates of AA and CC

From the graph:

  • Point AA is at (4,5)(4, 5)
  • Point CC is at (2,0)(2, 0)

Step 2: Use the section formula

Since ABAB is 3 times as long as BCBC, the ratio of the distances is AB:BC=3:1AB:BC = 3:1. The section formula gives the coordinates of a point that divides a line segment in a given ratio.

The section formula for dividing a line segment between points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) in the ratio m:nm:n is:

(x,y)=(mx2+nx1m+n,my2+ny1m+n)(x, y) = \left( \frac{mx_2 + nx_1}{m+n}, \frac{my_2 + ny_1}{m+n} \right)

Here, we want to divide AC\overline{AC} in the ratio 3:13:1, with:

  • A=(4,5)A = (4, 5)
  • C=(2,0)C = (2, 0)

Step 3: Apply the section formula

Plugging the values into the formula, with m=3m = 3 and n=1n = 1:

xB=32+143+1=6+44=104=2.5x_B = \frac{3 \cdot 2 + 1 \cdot 4}{3 + 1} = \frac{6 + 4}{4} = \frac{10}{4} = 2.5

yB=30+153+1=0+54=54=1.25y_B = \frac{3 \cdot 0 + 1 \cdot 5}{3 + 1} = \frac{0 + 5}{4} = \frac{5}{4} = 1.25

Step 4: Conclusion

The coordinates of point BB are (2.5,1.25)(2.5, 1.25).

Would you like a deeper explanation of any steps or additional details?

Here are 5 related questions for further practice:

  1. How would you calculate the midpoint of AC\overline{AC}?
  2. If ABAB were twice as long as BCBC, what would the coordinates of BB be?
  3. Can you find the slope of line segment ACAC?
  4. How would you calculate the distance between points AA and CC?
  5. What would the coordinates of BB be if AB=BCAB = BC (equal length)?

Tip: The section formula is useful for dividing line segments into specific ratios, which is especially handy in coordinate geometry.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Ratios and Proportions
Section Formula

Formulas

Section formula: (x, y) = ((mx2 + nx1) / (m + n), (my2 + ny1) / (m + n))

Theorems

Section Formula for dividing a line segment in a given ratio

Suitable Grade Level

Grades 8-10