If the line L passes through two points a (2,1) and B (1, M2) (m ∈ R), then the range of inclination angle of the line L is () A. [0，π）B. [0，π4]∪[34π，π)C. [0，π4]D. [0，π4]∪(π2，π)

If the line L passes through two points a (2,1) and B (1, M2) (m ∈ R), then the range of inclination angle of the line L is () A. [0，π）B. [0，π4]∪[34π，π)C. [0，π4]D. [0，π4]∪(π2，π)

Let the inclination angle of the straight line AB be θ, 0 ≤ θ ＜ π. According to the calculation formula of the slope, we can get the slope of AB as k = 1 − M22 − 1 = 1-m2, which is easy to get k ≤ 1. From the relationship between the inclination angle and the slope, we can get Tan θ ≤ 1. From the image of tangent function, we can get the range of θ as [0, π 4] ∪ (π 2, π), so we choose D

If the straight line L passes through points a (1,2) and B (3, m ^ 2), the slope of the inclination angle is in the range of 0

Slope k = (M & # 178; - 2) / 2
∴2k+2=m²≥0
∴k≥-1
Tilt angle a, yes
tana=k≥-1
(0 & # 186; ≤ a ＜ 180 & # 186; and a ≠ 90 & # 186;)
∴a∈(180º,135º]∪[0º,90º)