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Asked: 2026-05-27T08:42:20+00:00

I am trying to understand trigonometry and the short answer is that I do

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I am trying to understand trigonometry and the short answer is that I do not.

I drew a little triangle to mess around with and I asked myself the question, “If I know the length of the hypotenuse and the angle, how do I find the length of the other edges?”.

Then I started reading. Apparently, the sine of angle A is supposed to equal the length of the opposite side divided by the length of the hypotenuse. So I figured that, using a right triangle, multiplying the length of the hypotenuse by the sine of the angle would yield the length of the opposing side.

1.414 / 1 = .707blahblah * 1.414 = 1 on my calculator.

But in every programming language I try sin(45.0) equals .8somethingsomething. I tried c++, c#, java, php, and lua.

Is the input not being interpreted as degrees? What unit is being used and how do I convert it? I’ve been seeing the word Radians, it would be helpful if someone could explain what a Radian is.

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1 Answer

  1. Editorial Team

    Radians are units of angular measure, like degrees, except that while there are 360 degrees in a circle, there are 2*pi (about 6.28) radians in a circle. You can convert degrees to radians by multiplying by pi (3.14159) and dividing by 180.

    The formula works if the triangle is a right triangle, and yes, most programming languages expect radians rather than degrees as arguments to functions like sin() and cos().

    Regarding the argument in the comments below: if you fix angle <BAC, side AB, and side BC, you can see that there are two possible positions for point C which preserve the the length D2 for side BC. Therefore <BAC, D1, and D2 do not fully determine a triangle.

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