I hope this is the right place to ask this question. Imagine a right triangle with vertices A,B and C and corresponding opposite sides a, b and c such that there is a right angle at B and side b is the hypontenuse. Let the length of side b = 1. If I label side a as sin(A) and side c as cos(A), then the Pythagorean theorem gives us [tex]sin^2(A)+cos^2(A)=1[/tex], which we believe to be true in general. Now use the same triangle but instead let the length of side a =1 and let us call side c "sinh(D)" and b (the hypotenuse) as "cosh(D)". Then the Pythagorean theorem gives us [tex]cosh^2(D)-sinh^2(D)=1[/tex], which we also believe to be true in general. My question is, where is angle D? Can it be constructed from this triangle or does it have to be found with pure computation (meaning without the aid of a diagram)?