Hello, juvenilepunk!
26. If two opposite angles of a quadrilateral measure 120°,
and the measure of the other angles are multiples of 10°,
what is the probability that the quadrilateral is a parallelogram?
The four interior angles of a quadrilateral add up to 360°.
Since , then: .
Since are multiples of 10°, there are 11 cases.
. .
. .
In only one case the quadrilateral is a parallelogram.
Code:
A * - - - - - - - - - * B
/ 120° 60° /
/ /
/ /
/ /
/ 60° 120° /
D * - - - - - - - - - * C
Therefore: .