Question 1159132
1. Diagonals of an isosceles trapezoid are perpendicular.
<pre>
Sometimes true:             Sometimes false

{{{drawing(200,500/3,-3,3,-1,4, 
locate(-.4,0,TRUE),
line(-2,0,2,0), line(-2,0,-1,3), line(-1,3,1,3), line(1,3,2,0), 
line(-2,0,1,3), line(2,0,-1,3) )}}}{{{drawing(500/3,200,-3,3,-1,4, 
locate(-.4,0,FALSE),
line(-2,0,2,0), line(-2,0,-1,3), line(-1,3,1,3), line(1,3,2,0), 
line(-2,0,1,3), line(2,0,-1,3) )}}}

</pre>2. Adjacent sides of a rectangle are congruent.<pre>

Sometimes true (when the rectangle is a square)  Sometimes false:


{{{drawing(200,500/3,-3,3,-1,4, 
locate(-.4,0,TRUE),
line(-1.5,0,-1.5,3), line(-1.5,3,1.5,3), line(1.5,0,1.5,3), line(-1.5,0,1.5,0) )}}}{{{drawing(500/3,200,-3,3,-1,4, locate(-.4,0,FALSE),

line(-1.5,0,-1.5,3), line(-1.5,3,1.5,3), line(1.5,0,1.5,3), line(-1.5,0,1.5,0) )}}}



3. One pair of opposite sides of a trapezoid are congruent.

Sometimes true (when it's an isosceles trapezoid,  sometimes its false

{{{drawing(200,500/3,-3,3,-1,4, 
locate(-.4,0,TRUE),
line(-2,0,2,0), line(-2,0,-1,3), line(-1,3,1,3), line(1,3,2,0) )}}}{{{drawing(200,500/3,-3,3,-1,4, 
locate(-.4,0,FALSE),
line(-2,0,2,0), line(-2,0,-1,3), line(-1,3,2.2,3), line(2.2,3,2,0) )}}}

4. Sides of a rhombus are congruent.

<pre>Always true
{{{drawing(100,200,-2,2,-2,2, 

line(-1,0,0,-1), line(0,-1,1,0), line(1,0,0,1), line(0,1,-1,0) )}}}

5. Diagonals of a square are perpendicular. 
Always true
{{{drawing(100,200,-3,3,-3,3, 

line(-2,0,2,0), line(-2,0,-2,2), line(-2,2,2,2), line(2,2,2,0), 
line(-2,0,2,2), line(2,0,-2,2) )}}}



Edwin</pre>