Justify the following construction of the bisector of an angle with an inaccessible vertex:
https://cdn.artofproblemsolving.com/attachments/9/d/be4f7799d58a28cab3b4c515633b0e021c1502.png
M∈a and N∈b are taken, the 4 bisectors of the 4 internal angles formed by MN are traced with a and b. Said bisectors intersect at P and Q, then PQ is the bisector sought. geometryangle bisectorconstruction