Find angles between the lines and .
The angles between the lines are 30° and 150°.
Explanation
To find the angle between two lines, we need to find their slopes first and then apply the formula for angle between two lines. The context shows examples of finding slopes from line equations and working with angles in coordinate geometry problems.
Solution Steps
Step 1: Find the slope of the first line. From x + y = 1, we get y = -x + 1. Therefore, slope m₁ = -.
Step 2: Find the slope of the second line. From x + y = 1, we get y = (-1/)x + 1/. Therefore, slope m₂ = -1/.
Step 3: Apply the formula for angle between two lines: tan θ = |(m₁ - m₂)/(1 + m₁m₂)|
Step 4: Calculate m₁ - m₂ = - - (-1/) = - + 1/ = -2/
Step 5: Calculate m₁m₂ = (-)(-1/) = 1, so 1 + m₁m₂ = 2
Step 6: Therefore, tan θ = |-2/ ÷ 2| = 1/
Step 7: Since tan θ = 1/, we get θ = 30°
Step 8: The angles between two intersecting lines are θ and (180° - θ), so the angles are 30° and 150°.