Math Problem Statement

Find the equation of the circle passing through the three points(5,7), (8,1), (1,3)

Solution

To find the equation of the circle passing through three points, we use the general equation of a circle:

x2+y2+Dx+Ey+F=0x^2 + y^2 + Dx + Ey + F = 0

Where DD, EE, and FF are constants to be determined. We can substitute the coordinates of the given points (5,7)(5,7), (8,1)(8,1), and (1,3)(1,3) into the equation to form a system of equations.

Step 1: Substitute each point into the general equation

  1. For (5,7)(5,7): 52+72+5D+7E+F=05^2 + 7^2 + 5D + 7E + F = 0 25+49+5D+7E+F=05D+7E+F=74(Equation 1)25 + 49 + 5D + 7E + F = 0 \quad \Rightarrow \quad 5D + 7E + F = -74 \quad \text{(Equation 1)}

  2. For (8,1)(8,1): 82+12+8D+1E+F=08^2 + 1^2 + 8D + 1E + F = 0 64+1+8D+1E+F=08D+E+F=65(Equation 2)64 + 1 + 8D + 1E + F = 0 \quad \Rightarrow \quad 8D + E + F = -65 \quad \text{(Equation 2)}

  3. For (1,3)(1,3): 12+32+1D+3E+F=01^2 + 3^2 + 1D + 3E + F = 0 1+9+D+3E+F=0D+3E+F=10(Equation 3)1 + 9 + D + 3E + F = 0 \quad \Rightarrow \quad D + 3E + F = -10 \quad \text{(Equation 3)}

Step 2: Solve the system of equations

We now have the following system of linear equations:

5D + 7E + F &= -74 \quad \text{(Equation 1)} \\ 8D + E + F &= -65 \quad \text{(Equation 2)} \\ D + 3E + F &= -10 \quad \text{(Equation 3)} \end{aligned}$$ We can solve this system to find $$D$$, $$E$$, and $$F$$. Let me calculate that.The solution to the system of equations is: $$D = -\frac{29}{3}, \quad E = -\frac{19}{3}, \quad F = \frac{56}{3}$$ ### Step 3: Substitute $$D$$, $$E$$, and $$F$$ into the general equation of the circle The equation of the circle becomes: $$x^2 + y^2 - \frac{29}{3}x - \frac{19}{3}y + \frac{56}{3} = 0$$ Multiplying the entire equation by 3 to eliminate the fractions: $$3x^2 + 3y^2 - 29x - 19y + 56 = 0$$ Thus, the equation of the circle passing through the points $$(5,7)$$, $$(8,1)$$, and $$(1,3)$$ is: $$3x^2 + 3y^2 - 29x - 19y + 56 = 0$$ Would you like more details or have any questions? Here are five related questions to explore: 1. How can we find the center and radius of the circle from its equation? 2. How can we derive the equation of a circle given its center and radius? 3. Can the equation of a circle be represented in a different form, like the standard form? 4. How can we verify if another point lies on this circle? 5. What happens if the points given are collinear? **Tip:** The standard form of a circle's equation is $$(x - h)^2 + (y - k)^2 = r^2$$, where $$(h, k)$$ is the center and $$r$$ is the radius.

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Math Problem Analysis

Mathematical Concepts

Analytic Geometry
Circles
Systems of Linear Equations

Formulas

General equation of a circle: x^2 + y^2 + Dx + Ey + F = 0
Substitution method for solving systems of equations

Theorems

A circle can be uniquely determined by three non-collinear points
System of linear equations for solving circle parameters

Suitable Grade Level

Grades 10-12