Which statement is true about every parallelogram? 1) All four sides are congruent. 2) The interior angles are all congruent. 3) Two pairs of opposite sides are congruent. 4) The diagonals are perpendicular to each other. 1 2 O O O

a Argue that the midpoint of the hypotenuse of a right triangle is equidistant from the three vertices of the triangle. Use the fact that the congruent diagonals of a rectangle bisect each other. Be sure to provide a drawing. bUse the relationship from part a to find CM, the length of the median to the hypotenuse of right ABC, in which mC=90, AC = 6, and BC = 8.

For a given triangle such as ABC, what word describes the point of concurrency for athe three perpendicular bisectors of sides? _____________ bthe three altitudes? ____________________

In the accompanying figure, m2=68, m8=112, and m9=110. a.Which lines r and s OR l and m must be parallel? b Which pair of lines r and s OR l and m cannot be parallel?