Math Problem Statement

Find the acute angle between the lines, 2x-y=3, 3x+y=7

Solution

To find the acute angle between the two lines, we can use the formula for the angle θ\theta between two lines given by their slopes:

tanθ=m1m21+m1m2\tan \theta = \left| \frac{m_1 - m_2}{1 + m_1 m_2} \right|

where m1m_1 and m2m_2 are the slopes of the two lines.

Step 1: Find the slopes of the lines

The equation of a line in slope-intercept form is y=mx+cy = mx + c, where mm is the slope.

  • For the first line 2xy=32x - y = 3, we rewrite it as: y=2x3y = 2x - 3 So, the slope m1=2m_1 = 2.

  • For the second line 3x+y=73x + y = 7, we rewrite it as: y=3x+7y = -3x + 7 So, the slope m2=3m_2 = -3.

Step 2: Apply the formula

Now, substitute m1=2m_1 = 2 and m2=3m_2 = -3 into the formula:

tanθ=2(3)1+(2)(3)=2+316=55=1\tan \theta = \left| \frac{2 - (-3)}{1 + (2)(-3)} \right| = \left| \frac{2 + 3}{1 - 6} \right| = \left| \frac{5}{-5} \right| = 1

Step 3: Find the angle

We know that tanθ=1\tan \theta = 1 corresponds to θ=45\theta = 45^\circ.

Thus, the acute angle between the lines is 4545^\circ.

Would you like more details on any part of the solution?

Related Questions:

  1. How do you find the slopes of more complex lines?
  2. What is the geometric interpretation of the angle between lines?
  3. How do we handle lines that are parallel or perpendicular?
  4. Can you explain the difference between acute and obtuse angles between lines?
  5. What is the significance of the absolute value in the angle formula?

Tip: Always convert the line equations into slope-intercept form to easily identify the slope for calculations!

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Math Problem Analysis

Mathematical Concepts

Algebra
Analytic Geometry
Trigonometry

Formulas

\tan(\theta) = |(m_1 - m_2) / (1 + m_1 * m_2)|
Slope-intercept form y = mx + c

Theorems

Slope Formula
Tangent of Angle Between Two Lines

Suitable Grade Level

Grades 9-12