Comparing Angles: Lines with Slopes 2 and 1/2 on X-Axis

Question

Two straight lines have slopes of2,12 2,\frac{1}{2} .

Which of the lines forms a larger angle with the x axis?

Video Solution

Solution Steps

00:00 Find which of the lines has a larger angle with the X-axis
00:03 We'll use the formula to calculate slope based on the angle with the X-axis
00:07 We'll substitute the slope according to the given data and calculate to find the angle
00:12 We'll isolate the angle
00:18 This is the angle of the first line
00:24 We'll use the same method to find the angle of the second line
00:28 We'll substitute the slope according to the given data and calculate to find the angle
00:33 We'll isolate the angle
00:39 This is the angle of the second line
00:45 And this is the solution to the question

Step-by-Step Solution

To solve for which line forms a larger angle with the x-axis, we'll proceed by calculating the arctangent of each slope:

  • First, calculate the angle for the line with slope m1=2 m_1 = 2 :

θ1=tan1(2) \theta_1 = \tan^{-1}(2)

  • Next, calculate the angle for the line with slope m2=12 m_2 = \frac{1}{2} :

θ2=tan1(12) \theta_2 = \tan^{-1}\left(\frac{1}{2}\right)

Comparing these two results:

  • The function tan1(x) \tan^{-1}(x) is increasing, meaning as the value of x x increases, so does the angle θ \theta . Therefore, since 2>12 2 > \frac{1}{2} , it follows that θ1>θ2 \theta_1 > \theta_2 .

Therefore, the straight line with a slope of 2 forms the largest angle with the x-axis.

Answer

The straight line with a slope of 2 forms the largest angle.