Angles of a Parallelogram

Date: 8/24/96 at 13:47:47
From: Anonymous
Subject: Properties of Parallelogram Angles

In a parallelogram ABCD, angle ABC = 2 * angle BCD; what is the 
measure of ADC?

Date: 8/25/96 at 15:40:19
From: Doctor Robert
Subject: Re: Properties of Parallelogram Angles

You must remember that adjacent angles in a parallelogram are 
supplementary, that is, they add up to 180 degrees.  So, your problem 
becomes one of algebra.

If the measure of angle BCD is x, then the measure of angle ABC 
must be 2x.

Then we know that 2x + x = 180  so that x = 60 degrees.  Angle ADC
must have a measure of 120 degrees.

-Doctor Robert,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/