Two black lines pass through the origin, as shown below. If their slopes are \(2\) and \(5\), then find the slope of the red line that bisects the acute angle between these lines.
I answered a similar question here: https://web2.0calc.com/questions/coordinates_33120
We can find the slope thusly :
slope = tan [ (arctan (5) + arctan(2) ) / 2 ] = ( 9 + sqrt 130) / 7