Can you assume straight angles

The great unwashed masses taking the GRE will fall into this erroneous assumption, and all its implications, like lemmings running to the sea. In fact, because the diagram specifies no lengths or angles, it could be any one of the following:. You always have to have your visual imagination warmed up for possible alternatives, with different lengths and different angles. Any angle could be the largest or smallest angle.

Any side could be the largest or smallest side. The shape could look not even vaguely like the explicit diagram that appears. For example, in 1 above, the text specifies that the figure is a rectangle, so this means you can assume it has all the properties of rectangles four right angles, congruent opposite sides, etc. If nothing is marked or specified, you are falling into a trap to assume that an angle that looks right in the diagram truly is right.

If lengths appear equal, they may not be. That is the next proposition. The hypothesis of Proposition 13 is that the straight line which stands on the other makes two angles. But how could it not make two angles?

If it stood at the extremity of the line. In that case, it would make only one angle. When it does not stand at the extremity, however, then the angles formed are equal to two right angles.

Conversely -- if angles. This is Proposition But there is no previous proposition or definition that gives a criterion for two straight lines being in a straight line. This proposition is the criterion. Can supplementary angles assume? Can you assume congruent angles? What does AAS mean in geometry? How do you use AAS? What is AAS in physical education? Is AAA a thing in geometry?

Password recovery. Go Pro! Assumptions about Diagrams. Assumptions about Diagrams One thing that many geometry textbooks don't adequately address is the question of what kinds of assumptions we can make based on a diagram that is given to us in a problem. Assumptions you can't make If two segments look congruent, you may not assume that they are.

If two segments don't look congruent, you may not assume that they aren't. If one segment looks longer than another, you may not assume that it really is. If an angle looks like a right angle, you may not assume that it is. If an angle looks acute or obtuse, you may not assume that it is.