Get the angle of two cross line

Question

I want to get the angle of crosspoint of line A and B.

LineA = a1(100.0,100.3) to a2(100.1,100.2)
LineB = b1(100.0,100.1) to b2(100.1,100.4)

This Line A and Line B are crossed.

But how can I get the angle of cross point??

double a1x = 100.0;
double a1y = 100.3;
double a2x = 100.1;
double a2y = 100.2;
double b1x = 100.0;
double b1y = 100.1;
double b2x = 100.1;
double b2y = 100.4;

It is general programming question.

Not necessary the answer to the specific language.

I can use tanToRadian() method to calculate radian, so get tangent is OK.

and use Math.sqrt() to square the number.

Please give me a hint.

[Finding the angle between two line equations](https://math.stackexchange.com/q/1269050) — zero298, Jan 15 '19 at 21:49

score 2 · Accepted Answer · answered Jan 15 '19 at 21:55

2

Just apply its formula:

const ma = (100.2 - 100.3)/(100.1 - 100.0)
const mb = (100.4 - 100.1)/(100.1 - 100.0)

const tgx = Math.abs((ma - mb)/(1 + ma*mb));

const resp = tanToRadian(tgx);

(Not tested once you did not provide tanToRadian() func

answered Jan 15 '19 at 21:55

guijob

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I would also suggest using `Math.atan()` instead of OP's mysterious function. – Aioros Jan 15 '19 at 22:26

Get the angle of two cross line

1 Answers1