How to find angle between two lines?

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Beulah A
Beulah A am 21 Okt. 2019
Verschoben: Dyuman Joshi am 9 Jan. 2024
For example, there is line L1 between two points (x1,y1) and (x2,y2). Another line L2 between points (x1,y1) and (x3,y3). I want to find the angle between the lines L1, L2. How to find in MATLAB? I think in matlab there is no predefined function which performs the same.
  2 Kommentare
sudeep
sudeep am 7 Jan. 2024
Verschoben: Dyuman Joshi am 9 Jan. 2024
TURE AND
Example 1: Find the angle between r1 = 2(1 + cost) and r23(1-cost) and plot the graph for the same.

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Akzeptierte Antwort

Bjorn Gustavsson
Bjorn Gustavsson am 21 Okt. 2019
A more stable method that what Jos suggested is
v_1 = [x2,y2,0] - [x1,y1,0];
v_2 = [x3,y3,0] - [x1,y1,0];
Theta = atan2(norm(cross(v_1, v_2)), dot(v_1, v_2));
HTH
  3 Kommentare
jari jafri
jari jafri am 4 Okt. 2023
Bearbeitet: jari jafri am 4 Okt. 2023
I got my V_1 and V_2 vectors as
v_1 =
1×3 int32 row vector
-633 990 0
v_2 =
1×3 int32 row vector
0 500 0
But i am having the following error so I 'm looking for how to remove this error
Error using norm
First argument must be single or double.
Error in test6 (line 64)
Theta = atan2(norm(cross(v_1, v_2)), dot(v_1, v_2));
I'm getting this error while using this code
Dyuman Joshi
Dyuman Joshi am 4 Okt. 2023
@jari jafri convert the data to double -
v_1 = int32([-633 990 0]);
v_2 = int32([0 500 0]);
v_1 = double(v_1);
v_2 = double(v_2);
Theta = atan2(norm(cross(v_1, v_2)), dot(v_1, v_2))
Theta = 0.5689

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Weitere Antworten (2)

Jos (10584)
Jos (10584) am 21 Okt. 2019
Use the dot product between the two vectors (v1 and v2) given by the four x,y pairs points.
Given the formula: dot(v1,v2) = | v1 | x | v2 | x cos(A)
I leave it to you to find the angle A using the matlab functions norm, dot and acos.

Bjorn Gustavsson
Bjorn Gustavsson am 21 Okt. 2019

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