Video narration
How can we find a point exactly five centimetres away from two given points? Let's construct it using a compass! Our house has base DE, five centimetres long, and walls BD and CE, each five centimetres. B and C are their tops; the roof is open. So, AB equals AC equals five centimetres. Set the compass with a ruler to five centimetres, and keep that opening. Now let's use this same compass opening to find point A! From B, draw an arc above the house. Every point on it is five centimetres from B. Without changing the opening, draw an arc from C; every point on this arc is five centimetres from C. Where the arcs meet above the house is A, the roof peak. The arcs also meet below; choose the upper crossing. A is exactly five centimetres from both B and C.