How find rotation btween two points XY and XY

[raven jay]

what

[opaque sandal]

Have you tried using the Pythagorean theorem?

$a^2 + b^2 = c^2$

[frigid warren]

f0xy

[opaque sandal]

No

A triangle has three sides a, b and c. As does your picture.

Assuming that the angle to left is 90 degress, we can apply the Pythagorean theorem.

Once you established that you would have to use sin or cos

ok

Wait

there's an even simpler solution

Do you know how to work with tan($\alpha$)?

[frigid warren]

f0xy

[opaque sandal]

tan($\alpha$) is an mathematical operation

[frigid warren]

f0xy

[opaque sandal]

and $\alpha$ is an angle

[frigid warren]

f0xy

[opaque sandal]

your rotation

so you need the point?

or do you want the angle

?

So tan($\alpha$) = $\frac {opposite} {adjacent}$ inside a triangle with one angle being 90 degrees

[frigid warren]

f0xy

[opaque sandal]

If we take your example from earlier with one side being the length of 3 and the other one 4. This would look like tan($\alpha$) = $\frac {4} {3}$.

[frigid warren]

f0xy

[opaque sandal]

But wait

no

$\alpha$ is still unknown

[frigid warren]

f0xy

[opaque sandal]

now you would have to to the following

[frigid warren]

f0xy
Compile Error! Click the reaction for more information.
(You may edit your message to recompile.)

[opaque sandal]

You would have to tan^-1(4/3)

that's your alpha

[thick aspen]

$$\alpha =tan^{-1}(\frac{4}{3})$$

[opaque sandal]

yes

[frigid warren]

animeonfire

[opaque sandal]

yes

that would calculate your angle

assuming that your sides are the length 3 and 4 as above.

[thick aspen]

What is the actual problem? Like, you have that example, but what is the question?

[opaque sandal]

He's trying to find the angle here

i just explained him how to calculate that

[thick aspen]

For this one there is an even easier solution

[opaque sandal]

really?

[thick aspen]

Cause when you take the x and y difference between the points you find that both legs of the triangle are equal to 1

Since the angle in the bottom left corner is (most likely) a 90° angle, we have that (since the other two angles need to be of equal size) that the other angles are both equal to 45°

Given that the sum of inner angles in any triangle is always 180°

Yep

Lemme quickly look up the english term for that

That kind of triangle is an isosceles triangle, if you ever wanna learn more about it

[thick aspen]

Btw, are you german?

But the equation is flawed, even if it means the right thing:
Take the total sum (180°).
Subtract 90°, as this is the right angle.
Then you have 90° left.
Since the other angles (by construction of an isosceles triangle) are always equal, they both must be equal to X°.
Therefore, 90°=2×X°
And finally X°=45°

[cursive pond]

you dont

[opaque sandal]

yes. wby?