I probably need help with maths, rather than specifically with your calculator.

I'm trying to figure out the rotation of an image (the whole image is rotated within a filetype/programme where I cannot measure the rotation). This screenshot here is just representational: the angle is much smaller; the image is shown as a frame.

NANY 2017: Calculor - A Live, Handy, Dandy, Inline CalculatorRight-angled triangle => I need measurements for an angle. Using measurements for two sides:

adjacent

opposite

Tangent = opposite/adjacent

0.0078294071615532 = 1.45075/185.295

according to your (very good) help:

Inverse Tangent

atan(tan)

Finds the angle of the Hypotenuse when given Tangent

atan(0.0078294071615532) = 0.000137

but the results I get above appear to be wrong - the programme I used to rotate the image cannot make such a small rotation. Rotating back, I estimate the rotation at circa 0.45°. (Should this not be the same as the measure of the angle - or am I misunderstanding?)

Can anyone see am I doing something wrong?

(I've double checked the measurements, they are correct. I can measure the third side if that any help.)