Posted by Mason on Thursday, April 7, 2011 at 10:35pm.
Which statement is always true about a parallelogram?
A. It has 4 congruent sides
B. It has 4 right angles.
C. It has opposite angles that are congruent.
D. The sum of any 3 angles is 360
Is it a?

Math  angelica, Thursday, April 7, 2011 at 10:36pm
B.it has 4 right angles

Math  Jai, Thursday, April 7, 2011 at 10:42pm
hmm,, recall that when we consider a parallelogram, we also consider square, rhombus, and rectangle (they are all parallelogram)
now, let's analyze each choices:
for (a), it's only true for a square.
for (b), it's true for square and rectangle.
for (c), it's true for any parallelogram
for (d), it's wrong, since sum of all four angles must be 360.
thus the answer is (c).
hope this helps~ :) 
Math  Anonymous, Thursday, April 7, 2011 at 11:29pm
Properties of Parallelogram:
Opposite sides of a parallelogram are parallel and so will never intersect.
Opposite sides of a parallelogram are equal in length.
Opposite angles of a parallelogram are equal in measure.
Adjacent angles are supplementary (add up to 180°).
The area of a parallelogram is twice the area of a triangle created by one of its diagonals.
The diagonals of a parallelogram bisect each other.
Any line through the midpoint of a parallelogram bisects the area.
The perimeter of a parallelogram is 2(a + b) where a and b are the lengths of adjacent sides.
The sum of the squares of the sides equals the sum of the squares of the diagonals.