How was trade between europe and africa before the 1400s different from trade between those continents between the 1400s and the 1700s

The correct answer is:

Trade between Europe and Africa before the 1400s was indirect. Between the 1400s and the 1700s, it was direct.

In the 15th century, Africa developed regular contact with the rest of the world for the first time. Before that, all external association had been indirect and slow. Although language, technology, and precious objects had affected peoples’ lives, there wasn't a regular contact. In the 15th century, Africa initiated direct relations both with the Mediterranean world of Islam and with the European world of Christendom.

answer: this problem has only trivial solutions, with all points on the same line. x=5 or x=7/5.

step-by-step explanation:

there are three triangles, and three unknowns: x, y=length of middle segment, and z=cos(angles marked with red arc).

we need

and law of cosines,

the three equations are

see attached image for solution.