Mathematics for IGCSE & O level - Coordinate Geometry (Section 1 - No. 27)
If a line has a gradient of 3, what is the gradient of a line perpendicular to it?
-3
1/3
-1/3
3
คำอธิบาย
The gradient of a perpendicular line is the negative reciprocal. The negative reciprocal of 3 is -1/3.