adjacent is the opposite side of a right angle triangle.
adjacent is the opposite side of a right angle triangle.
what is the opposite side of a right angle triangle?
adjacent
section::::volume 1.:diagram of a round town.









































the monography begins with a master diagram called the diagram of round town(圆城图式). it shows a circle inscribed in a right angle triangle and four horizontal lines, four vertical lines.









































bullet::::- tlq, the large right angle triangle, with horizontal line lq, vertical line tq and hypotenuse tl









































c: center of circle:









































bullet::::- ncs: a vertical line through c, intersect the circle and line lq at n(南north side of city wall)， intersects south side of circle at s(南).









































bullet::::- ncsr, extension of line ncs to intersect hypotenuse tl at r(日)
ceyuan haijing
in ancient times it was known that a triangle whose sides were in the ratio 3:4:5 would have a right angle as one of its angles. this was used in construction and later in early geometry. it was also known to be one example of a general rule that any triangle where the length of two sides, each squared and then added together , equals the square of the length of the third side , would also be a right angle triangle.
fermat's last theorem