Posted by properties of triangle on Friday, January 28, 2011 at 12:36am.
the exterior angle 120degre and one interior angle 45degre of each triangle are given.find the other interior opposite angle and the third angle of each triangle.

geometry  drwls, Friday, January 28, 2011 at 12:45am
The interior angle associated with the 120 degree exterior angle is its supplement: 60 degrees. With interior angles of 45 and 60 degrees, the third interior angle must be 180  105 = 75 degrees

geometry  helper, Friday, January 28, 2011 at 12:45am
See your first post.

geometry  helper, Friday, January 28, 2011 at 12:47am
Thanks drwls. I could not understand this post at all. :)