How do I calculate the Slope of a Perpendicular Line ?
Given the slope of Line 1, how do I calculate the slope of the Perpendicular Line [Line 2] ?
Answer
If Line 1 has Slope = m1 and the perpendicular Line 2 has slope m2, then it must be that (m1) x (m2) = -1.
Example : What is the slope of the line perpendicular to the Line 1, y= 3x + 5 ?
Solution : m1=3 so m2 = -1/(m1) after rearranging to solve for m2. Plugging in, we have m2= -1/3.
Example 2: Line 1, y= (1/4)x + 3. m1= 1/4. m2= -1/m1 = -1/(1/4) = -4.