100 Doors World of History Level 100 Guide:
Figure out the hypotenuse.
Split triangle in half. Sides = 80 and 60
Figure out an angle (I used bottom right corner) = Tan (angle) = 80/60 = Angle = about 53.13
Cos (53.13) = 60/hypotenuse. Hypotenuse = 100
Congratulations! You've completed 100 Doors World of History! Sequel coming soon.