A very simple equation indeed. Look at the ry1 .
Look at the ry1 and see how easy two equations with two unknowns are .
Well this question is to check your eyes. The smallest difference between these segments (between 3 and 4) is about 1/4 ths of a millimeter. Some
may have difficulties in differentiating. A single hair is about 60 μm. (a μm. is 1/1000 ths of a millimeter), about 1/4 ths of the minimal difference of our segments. Most
of us see a sigle hair.
∠a and ∠c are congruent .
The choice is obvious, the question is just for remembrance and the next question .
Look at the definition of Radian and try to understand .
Since the sum of inner angles of a rectangle is 360 degrees, the right triangle must have ... .
Since the adjacent angles at the bottom of I and II are both 90 degrees , the remaining angles in both triangles should have a total of 90
All we know is still m(∠1 + ∠3) = m(∠d + ∠a) .
An alternate interior and its adjacent alternate exterior have a total measure of 180 degrees .
Alternate interior of B is the vertical of 3 .
It is supposed to lead to an equivalent geometry . The one we have is simple enough.
Equivalency left aside, maybe due to being conditioned, I can not imagine any candidate. And I can not show the impossibility. So it remains open.