What is the inclination of the line that passes through the points (8,2) and (12,6)?

Inclination of the line is the angle made by the line to x
axis.

The inclination of the line depends on the gradient
of that line.

The gradient of the line is the ratio between
the changes in y direction and changes in x direction.

The
inclination of the line is the slope of that line.

 m = (y2
- y1)/(x2 - x1)

We notice that the numerator and
denominator represents the legs of a right triangle.

m =
tan a, where a is the angle made by the line and x axis.

x1
= 8 and x2 = 12

y1 = 2 and y2 =
6

tan a = (6 - 2)/(12 - 8)

tan
a = 4/4

tan a =
1

The inclination of the line with respect to
x axis is the angle a = pi/4 or 45 degrees.