The 3 ancient Greek Problems are:
1. Trisect a Triangle
2. Square a circle
3. Doubling a Cube
Why restrict using only unmarked ruler ?
Answer: Using a Straight line: $latex boxed{ y = mx + c } $
Why a compass?
Answer: Using a Circle: $latex boxed{ x^2 + y^2 = r^2 }$
The 3 Greek Problems have been proven by 19th Century impossible to solve with only a straight line and a circle.
Mathtuition88 