![]() You know two of the angles, then you know what the ![]() These two triangles are similar? Well, sure. Is congruent to this angle, and that angle right there Two of the corresponding angles are congruent. Let me draw it like this- and if I told you that only Have another triangle that looks like this. Two angles for a triangle, you know the third. But do you need three angles? If we only knew two of theĪngles, would that be enough? Well, sure because if you know B and Y, which are the 90ĭegrees, are the second two, and then Z is the last one. Order right to make sure that you have the rightįirst two things. Know that triangle ABC is similar to triangle XYZ. So we would know from thisīecause corresponding angles are congruent, we would This is 90 degrees,Īnd this is 60 degrees, we know that XYZ in this case, And we have anotherĬlearly a smaller triangle, but it's corresponding angles. This angle right over here is 60 degrees. This is 30 degrees, this angle is 90 degrees, and So we already knowĪngles are congruent to the correspondingĪngles on ABC, then we know that we're dealing Whether another triangle is similar to triangle ABC. I want to come up withĪ couple of postulates that we can use to determine Some of these involve ratios and the sine of the given angle. There are some other ways to use SSA plus other information to establish congruency, but these are not used too often. If the given angle is right, then you should call this "HL" or "Hypotenuse-Leg", which does establish congruency. ![]() ![]() However, you shouldn't just say "SSA" as part of a proof, you should say something like "SSA, when the given sides are congruent, establishes congruency" or "SSA when the given angle is not acute establishes congruency". If the side opposite the given angle is longer than the side adjacent to the given angle, then SSA plus that information establishes congruency. SSA establishes congruency if the given sides are congruent (that is, the same length). SSA establishes congruency if the given angle is 90° or obtuse. However, in conjunction with other information, you can sometimes use SSA. SSA alone cannot establish either congruency or similarity because, in some cases, there can be two triangles that have the same SSA conditions. ![]()
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