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Across 2. Points that lie in the same line 5. A segment, line, or plane that intersects a segment at its midpoint. 6. The sum of the lengths of the sides of a polygon 9. Two angles that have a sum of 180 degrees and are adjacent angles whose non-common sides are opposite rays and 11. A polygon for which there is a line containing a side of the polygon that also contains a poin in the interior of the polygon 12. Lines that intersect to form four right angles 14. The point halfway between the endpoints of a segment 15. The intersection of two non-collinear rays at a common endpoint. 16. An angle whose degree measure is greater than 90 degrees but less than 180 degrees 17. Two angles that have a sum of 180 degrees 18. Points that lie in the same plane

Down 1. Two angles that have a sum of 90 degrees 3. A basic undefined term of geometry which is made up of points and has no thickness or width 4. An angle whose degree measure is less than 90 degrees but greater than 0 degrees 7. Two angles that lie in the same plane, have a common vertex and a common side, but no common interior points 8. Having the same measure 10. A ray that divides an angle into two congruent angles 13. Lines that never intersect and are equidistant everywhere