Question

how to make a 45degree angle using compass

Answer 1

This how 45° angle is created using compass

Answer 2

first draw a line . take the measure of compass more than the half length of the line and draw the arc do the same from the other point of line.
now draw the draw the line through the intersection of two arc and draw an perpendicular line of the straight line.
now take an arc on straight line and on the perpendicular line and draw a angle bisector. hence join the angle bisector.
your 45 degree angle is completed.

here is your answer.
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