Question

if you didn't have a protractor how could you reconstruct a quarter of it from 0 to 90 degrees ?

Answer 1

Measure exactly the same length for example 5 inches and 5 inches and make the two ends of the lengths meet and put a small square at the bottom corner to make it a 90 degree angle. 

Answer 2

Or you can use the corner or a piece of paper that is 90‍♂️