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**1.**parallelogram with four congruent sides**5.**when the hypothesis and the conclusion is switched**10.**the side opposite the right angle in right triangle**12.**a statement that follows immediately from a theorem**13.**quadrilateral with two pairs of adjacent sides congruent and no opposite sided congruent**16.**a line that intersects two coplanar lines at two distinct points**17.**lines two lines that intersect to form right angles**18.**a line that intersects a circle at two points**19.**the space that a figure occupies**20.**when three or more lines intersect in one point**21.**a transformation whose preimage and image are similiar

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**2.**a segment connecting the midpoints of two sides**3.**two figures that have the same shape but not necessarily the same size**4.**a statement that two ratios are equal**6.**angle an angle whose vertex is the center of the circle**7.**the distance around a circle**8.**formed by two rays with the same endpoint**9.**a segment whose endpoints are on a circle**11.**all sides congruent**14.**another name for an if-then statement**15.**an isometry in which a figure and its image have opposite orientations**17.**a three-dimensional figure whose surface are polygons