Math Problem Statement

Find the area of a triangle bounded by the y

axis, the line f(x)=-2/9x+5

, and the line perpendicular to f(x)

that passes through the origin.

Solution

To find the area of the triangle bounded by the y-axis, the line f(x)=29x+5f(x) = -\frac{2}{9}x + 5, and the line perpendicular to f(x)f(x) that passes through the origin, follow these steps:

  1. Identify the slope of the perpendicular line:
    The given line has a slope of 29-\frac{2}{9}. The slope of a line perpendicular to this will be the negative reciprocal of 29-\frac{2}{9}, which is 92\frac{9}{2}.

  2. Equation of the perpendicular line:
    Since this line passes through the origin (0,0)(0, 0), its equation is: y=92xy = \frac{9}{2}x

  3. Find the intersection point of the two lines:
    Set the equations equal to find the intersection point. 29x+5=92x-\frac{2}{9}x + 5 = \frac{9}{2}x Multiply through by 18 to clear the fractions: 4x+90=81x-4x + 90 = 81x Combine like terms: 90=85x90 = 85x Solve for xx: x=9085=1817x = \frac{90}{85} = \frac{18}{17} Substitute x=1817x = \frac{18}{17} back into one of the line equations to find yy: y=92(1817)=8117y = \frac{9}{2} \left( \frac{18}{17} \right) = \frac{81}{17} So, the intersection point is (1817,8117)\left( \frac{18}{17}, \frac{81}{17} \right).

  4. Find the vertices of the triangle:

    • One vertex is at the origin: (0,0)(0,0).
    • Another vertex is at the y-intercept of f(x)=29x+5f(x) = -\frac{2}{9}x + 5, which is (0,5)(0, 5).
    • The third vertex is the intersection point: (1817,8117)\left( \frac{18}{17}, \frac{81}{17} \right).
  5. Calculate the area of the triangle:
    Using the vertices (0,0)(0, 0), (0,5)(0, 5), and (1817,8117)\left( \frac{18}{17}, \frac{81}{17} \right), use the formula for the area of a triangle with vertices (x1,y1)(x_1, y_1), (x2,y2)(x_2, y_2), and (x3,y3)(x_3, y_3): Area=12x1(y2y3)+x2(y3y1)+x3(y1y2)\text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| Substituting in our points: Area=120(58117)+0(81170)+1817(05)\text{Area} = \frac{1}{2} \left| 0(5 - \frac{81}{17}) + 0(\frac{81}{17} - 0) + \frac{18}{17}(0 - 5) \right| Simplify inside the absolute value: Area=121817(5)=129017=129017=4517\text{Area} = \frac{1}{2} \left| \frac{18}{17}(-5) \right| = \frac{1}{2} \left| -\frac{90}{17} \right| = \frac{1}{2} \cdot \frac{90}{17} = \frac{45}{17}

So, the area of the triangle is 4517\frac{45}{17} square units.

Would you like more details or have any questions?

Here are 8 related questions that expand on this information:

  1. How do you find the equation of a line given a point and a slope?
  2. What is the negative reciprocal of a slope, and why is it important for perpendicular lines?
  3. How do you find the y-intercept of a line given its equation?
  4. How do you solve for the intersection point of two lines?
  5. What is the general formula for the area of a triangle given its vertices?
  6. Can you explain the steps to convert a linear equation into slope-intercept form?
  7. How would the process change if the triangle was bounded by different lines?
  8. What are some real-world applications of finding the area of a triangle using coordinates?

Tip: Always double-check your calculations for intersection points and area, as small arithmetic errors can lead to incorrect results.

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Math Problem Analysis

Mathematical Concepts

Geometry
Linear Equations
Perpendicular Lines
Coordinate Geometry

Formulas

Area of a Triangle

Theorems

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Suitable Grade Level

High School