If two adjacent angles have their non-common sides in the same straight line, then they are always . . .?
d)Supplementary. a straight line is 180 degrees. if 2 angles form this straight line, they add up to 180 degrees. this makes them supplementary.
Is it true that if two angles share a common side, then they're adjacent?
adjacent means that things are right next to each other, so yes
How do I prove that two adjacent angles of any parallel sides of a trapezium are equal?
It depends a bit on your nationality.If you’re British, you mostly don’t.And if you’re not, you usually can’t.The reason is that there are two definitions for trapezium - one involves parallel sides, and the other doesn’t.The other reason is that even if there is a pair of parallel sides, the angles are not equal. The only time the angles will be equal is if the parallel sides share a common centre. Or the line joining the two parallel sides is perpendicular to those sides.The easiest proof was created by a computer program designed to solve geometric problems. It is believed that this solution was previously unknown, but I suspect it had been discovered independently by hundreds of children who were promptly told don’t be silly you can’t do that it’s not the way it’s done.But when the computer said “Turn it over. It’s the same figure, therefore the angles are equal”, it was believed.I’m sure you can find a more traditionally rigorous proof using congruent triangles. First extend the sides to form a triangle.
Two angles that share a common side and are supplementary?
What's which angle called? The two angles are supplementary, so they add up to 180°, but I don't know what else you're looking for.
Two triangles with an equal base share a common side. Can the angle between them be equal?
They can be, as in your diagram, but they do not have to be as in the diagram below. So, no, unless you have other information about the triangles that you have not shared, you can’t use it as a reason.
Can two adjacent angles be supplementary?
Adjacent angles can be supplementary in two different ways: on a line and in quadrilaterals.1. Draw a line ABC. From B draw a line BD at any angle other than a right angle.Now