Math Problem Statement

Find circumcenter of a triangle whose vertices are (0, 4) (5, 0) and (- 2, 3).

Solution

The circumcenter of a triangle is the point where the perpendicular bisectors of the sides of the triangle meet. It is equidistant from the vertices of the triangle.

Steps to Find the Circumcenter:

  1. Identify the vertices of the triangle:
    A(0,4)A(0, 4), B(5,0)B(5, 0), C(2,3)C(-2, 3).

  2. Calculate the midpoints of two sides of the triangle:

    • Midpoint of ABAB: Midpoint of AB=(x1+x22,y1+y22)=(0+52,4+02)=(2.5,2).\text{Midpoint of } AB = \left(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\right) = \left(\frac{0 + 5}{2}, \frac{4 + 0}{2}\right) = (2.5, 2).
    • Midpoint of ACAC: Midpoint of AC=(x1+x22,y1+y22)=(0+(2)2,4+32)=(1,3.5).\text{Midpoint of } AC = \left(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\right) = \left(\frac{0 + (-2)}{2}, \frac{4 + 3}{2}\right) = (-1, 3.5).
  3. Find the slopes of the sides:

    • Slope of ABAB: mAB=y2y1x2x1=0450=45.m_{AB} = \frac{y_2 - y_1}{x_2 - x_1} = \frac{0 - 4}{5 - 0} = -\frac{4}{5}.
    • Slope of ACAC: mAC=y2y1x2x1=3420=12=12.m_{AC} = \frac{y_2 - y_1}{x_2 - x_1} = \frac{3 - 4}{-2 - 0} = \frac{-1}{-2} = \frac{1}{2}.
  4. Calculate the perpendicular slopes:

    • Perpendicular slope to ABAB: mAB=1mAB=54.m_{\perp AB} = -\frac{1}{m_{AB}} = \frac{5}{4}.
    • Perpendicular slope to ACAC: mAC=1mAC=2.m_{\perp AC} = -\frac{1}{m_{AC}} = -2.
  5. Write the equations of the perpendicular bisectors:

    • Perpendicular bisector of ABAB (passing through (2.5,2)(2.5, 2)): y2=54(x2.5).y - 2 = \frac{5}{4}(x - 2.5). Simplify: y=54x258+2=54x98.y = \frac{5}{4}x - \frac{25}{8} + 2 = \frac{5}{4}x - \frac{9}{8}.
    • Perpendicular bisector of ACAC (passing through (1,3.5)(-1, 3.5)): y3.5=2(x+1).y - 3.5 = -2(x + 1). Simplify: y=2x2+3.5=2x+1.5.y = -2x - 2 + 3.5 = -2x + 1.5.
  6. Solve the two equations to find the intersection point:

    • From y=54x98y = \frac{5}{4}x - \frac{9}{8} and y=2x+1.5y = -2x + 1.5, equate: 54x98=2x+1.5.\frac{5}{4}x - \frac{9}{8} = -2x + 1.5.
    • Clear fractions by multiplying through by 8: 10x9=16x+12.10x - 9 = -16x + 12. Simplify: 26x=21    x=2126.26x = 21 \implies x = \frac{21}{26}.
    • Substitute x=2126x = \frac{21}{26} into y=2x+1.5y = -2x + 1.5: y=2(2126)+1.5=4226+3926=326.y = -2\left(\frac{21}{26}\right) + 1.5 = -\frac{42}{26} + \frac{39}{26} = -\frac{3}{26}.

Thus, the circumcenter of the triangle is: (2126,326).\boxed{\left(\frac{21}{26}, -\frac{3}{26}\right)}.


Would you like me to elaborate on any step or provide a graphical representation?

Follow-up Questions:

  1. What are the properties of the circumcenter in different types of triangles?
  2. Can the circumcenter fall outside the triangle? If yes, when does that occur?
  3. How is the circumradius related to the circumcenter?
  4. How do you find the circumcenter of a triangle in 3D space?
  5. How does the circumcenter relate to the Euler line of a triangle?

Tip: Always double-check calculations when solving equations with fractions to avoid arithmetic errors!

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangles
Coordinate Geometry
Perpendicular Bisectors
Intersection of Lines

Formulas

Midpoint formula: (x1 + x2)/2, (y1 + y2)/2
Slope formula: (y2 - y1)/(x2 - x1)
Perpendicular slope: -1/m
Line equation: y - y1 = m(x - x1)

Theorems

Circumcenter theorem: The point of concurrency of the perpendicular bisectors of a triangle is equidistant from all vertices.

Suitable Grade Level

Grades 9-12