A shape is randomly selected from the following quadrilaterals: parallelogram, rhombus, rectangle, square, and trapezoid. What is the probability that it has four right angles, given that it has four congruent sides?

1/2.

Step-by-step explanation:

There are 2 quadrilaterals which have 4 congruent sides in the list: A square and a rhombus, The square  is the one with four right angles.

So the required  probability  is 1/2.

step-by-step explanation:

x^2 -12x + 36 + y^2 = 36

x^2 + y^2 = 12x

r^2 = 12rcos(theta)

r = 12 cos(theta)