##### Across

**4.**the measure of a regions size on a surface**6.**the branch of mathematics concerned with specific functions of angles and their application to calculations**8.**the branch of mathematics concerned with the properties and relations of points, lines,surfaces, solids,and higher dimensional analog**9.**the distance across a circle through the centre**12.**a point that is in the middle of the line joining two points**14.**a figure plane with four straight sides and four straight angles**16.**a half infinite line(also known as a half line) with one of the two points and taken to be at infinity**18.**a statement that can be demonstrated to be true by accepted mathematical operations and arguments**20.**the distance that surrounds a circle

##### Down

**1.**the space occupied within the boundaries of an object in three-dimensional space**2.**a two dimensional shape with 4 sides, four vertices,and four angles**3.**a dot in a plane or a piece of paper**5.**a point where two or more curves, lines, or edges meet.**7.**the distance from the center of the circle to any point on its circumference**10.**three sided polygon**11.**a round plane figure whose boundary consists of points equidistant from a fixed point (the center)**13.**a polygon composed of four triangular faces, six straight edges, and four vertex corners.**15.**each pairs of opposite angles made by two intersecting lines**17.**a two dimensional doubly ruled surface spanned by two linearly independent vectors**19.**when both the hypotenuse and conclusion are negated