Geometry question

[mathlearner]

I am currently taking a college course in geometry. I am having difficulty understanding the difference between the ASA and SAS postulates. My textbook does not make the two postulates clear to me. How can it be determined whether a congruent triangle with or without markings of angles and sides be labeled as ASA or SAS? Also how can you tell when two triangles are not congruent? How many questions am I allowed to post on this site and within what time frame?

 

[mmm4444bot]

How many questions am I allowed to post on this site and within what time frame?

There is no set limit. From our FORUM GUIDELINES comes the following.

Don't post a list of homework problems. Please show us any work you have done towards answering the problem, and try to explain what specifically is giving you trouble. Also, please try to limit the number of questions you ask to a reasonable number per day. There's no exact limit, but try to be polite and not abuse the service.

I don't care very much about post numbers; I'm more concerned about posters submitting exercises without making any statements of their own.

I will not limit posters' numbers of posts, as long as they demonstrate some type of effort (eg: a little bit of work, explaining thoughts, asking specific questions, requesting lesson links or examples, or clarifying English phrases, math notation or symbols, et cetera).

Cheers :cool:

PS: One needs to be first provided with the information that certain sides or angles are equal, before those postulates are of any use proving congruency. If you have two unmarked triangles, then not much can be said about them.

 

[lookagain]

Also how can you tell when two triangles are not congruent?

A couple of ways out of a larger number of ways are:

1) If one of the triangles has at least one side length that is different from
any of the side lengths of the other triangle.

2) At least one of the measures of one of the angles in a triangle is different
than all of the measures of angles in the other triangle.

It suffices to have three equalities (ASA, SAS, SSS, or AAS)
to determine that all six equalities are true.

Here is another way:

RHS (Right-angle-Hypotenuse-Side): If two right-angled triangles have their
hypotenuses equal in length, and a pair of shorter sides are equal in length,
then the triangles are congruent.

Source: Wikipedia