You know how to make a 90° angle 
You could make a 45° angle by bisecting a 90° angle. 
You then bisect the 45° angle to make 22 ½° angle.
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The Brainliest Answer!
1)make a line.
2)mark a point A on the line.
3)taking point A as center draw a semicircle.
4)with same radius draw make an arc by taking the p of inter s. as center.
5)by taking point of inter s. of arc as center draw another arc.
6)bisect it.
7)you will get 45 angle.
8)bisect it you will get 22 1/2 degree angle.
hope it helped.
pls mark as brainliest.
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pls mark as brainliest
the option will be below the thanks option