Math Problem Statement

answer with complete solution

Solve the following problems: 1. Find the equation of the line whose x-intercept is 8 and y-intercept is -1. 2. Reduce 3x - 8y + 24 = 0 to the intercept form. 3. Reduce x + 6y - 7 = 0 to the normal form. Give the distance of the line from the origin. 4. What is the equation of a line through (5, 2) with the x-intercept thrice the y-intercept? 5. Find the equation of a line through (-4, -2) and forming with the coordinate axes a triangle with area 16. 6. Find the equations of the lines parallel to the line 3x + 4y - 12 = 0 and passing at distance ±3 from the origin.

Solution

Let's go through the problems one by one and solve them with detailed explanations.


1. Find the equation of the line whose x-intercept is 8 and y-intercept is -1.

To solve this, use the intercept form of the equation of a line:

xa+yb=1\frac{x}{a} + \frac{y}{b} = 1

where aa is the x-intercept and bb is the y-intercept.

  • Here, a=8a = 8 and b=1b = -1.

Substitute the values:

x8+y1=1\frac{x}{8} + \frac{y}{-1} = 1

Multiply through by 8 to eliminate the denominators:

x8y=8x - 8y = 8

This is the required equation of the line.


2. Reduce 3x8y+24=03x - 8y + 24 = 0 to the intercept form.

The intercept form is:

xa+yb=1\frac{x}{a} + \frac{y}{b} = 1

We need to manipulate the given equation to fit this form.

Start by moving the constant term to the other side:

3x8y=243x - 8y = -24

Now, divide the entire equation by 24-24 (the constant term on the right-hand side):

3x248y24=1\frac{3x}{-24} - \frac{8y}{-24} = 1

Simplify the fractions:

x8+y3=1\frac{x}{-8} + \frac{y}{3} = 1

Thus, the equation in intercept form is:

x8+y3=1\frac{x}{-8} + \frac{y}{3} = 1

where the x-intercept is 8-8 and the y-intercept is 33.


3. Reduce x+6y7=0x + 6y - 7 = 0 to the normal form. Give the distance of the line from the origin.

The normal form of a line is:

xcosθ+ysinθ=px \cos \theta + y \sin \theta = p

where pp is the perpendicular distance from the origin to the line and θ\theta is the angle the normal makes with the x-axis.

We begin by rewriting the given equation:

x+6y=7x + 6y = 7

Now, express it in the form:

Ax+By=CAx + By = C

where A=1A = 1, B=6B = 6, and C=7C = 7.

To reduce this to normal form, divide the equation by the length of the normal (which is the square root of A2+B2A^2 + B^2):

Length of the normal=12+62=37\text{Length of the normal} = \sqrt{1^2 + 6^2} = \sqrt{37}

Dividing the equation by 37\sqrt{37}:

x37+6y37=737\frac{x}{\sqrt{37}} + \frac{6y}{\sqrt{37}} = \frac{7}{\sqrt{37}}

This is the normal form of the line. The distance of the line from the origin is the constant term on the right-hand side:

Distance=7371.15\text{Distance} = \frac{7}{\sqrt{37}} \approx 1.15


4. What is the equation of a line through (5,2)(5, 2) with the x-intercept thrice the y-intercept?

Let the x-intercept be aa and the y-intercept be bb. We are told that the x-intercept is thrice the y-intercept, so:

a=3ba = 3b

Using the intercept form of the line equation:

xa+yb=1\frac{x}{a} + \frac{y}{b} = 1

Substitute a=3ba = 3b:

x3b+yb=1\frac{x}{3b} + \frac{y}{b} = 1

Now, multiply through by (b\

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Linear Equations
Intercept Form
Normal Form
Distance Formula
Triangle Area
Parallel Lines

Formulas

Intercept form: x/a + y/b = 1
Normal form: x cos θ + y sin θ = p
Distance formula: |Ax + By + C| / sqrt(A^2 + B^2)
Area of triangle: 1/2 * base * height

Theorems

Distance between a point and a line
Area of triangle in coordinate geometry

Suitable Grade Level

Grades 10-12