How to find angle between two lines?

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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.

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James Tursa 2019-10-21

https://www.mathworks.com/matlabcentral/answers/101590-how-can-i-determine-the-angle-between-two-vectors-in-matlab

sudeep 2024-1-7

移动：Dyuman Joshi 2024-1-9

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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Answer 1

Bjorn Gustavsson 2019-10-21

在 MATLAB Online 中打开

5 个投票

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

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jari jafri 2023-10-4

编辑：jari jafri 2023-10-4

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 2023-10-4

在 MATLAB Online 中打开

@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