Given that the coordinates of A and B are (2,a) and (1,1) respectively and the inclination of the line AB is 45 degree. Find the value of a. (with steps please and be quick please!! Thanks a lot!)

⚑ Flag

Yuen - A line that inclines at 45 degrees has a slope of 1.  Think of the line y=x and how it passes through the origin at 45 degrees relative to the x-axis.  Since you are taking trig, you can also find the slope by taking the tan 45 degrees.  This is consistent with tan m = y/x for coordinate (x,y) with slope m. For the point (1,1), m=1. Hope this helps