Congruent Triangles Terms
Get down with the lingo
AAS TheoremIf two corresponding angles and one of the sides not between the angles in any two triangles are congruent, the two triangles are congruent.
Acute TriangleA triangle that's slightly less cute than a-super-cute triangle. For that to be true, all the angles in the triangle have to be less than 90°.
Angle Sum TheoremAll the interior angles of a triangle add up to 180°. Always.
ASA PostulateIf two corresponding angles and the included side in any two triangles are congruent, the two triangles are congruent.
CongruenceWhen two objects are identical in every way. The only thing that separates them is a congruence transformation.
Congruence TransformationThese are transformations that create congruent figures once they're done, a.k.a. translation, rotation, and reflection. They're like little clone factories.
CPCTCStands for "Corresponding Parts of Congruent Triangles are Congruent." The "parts" we're talking about here are angles and sides, so don't go snooping at the local auto body shop.
Equilateral TriangleA triangle with all three side lengths that are equal. All three angles are also equal (all are 60°). If it has three of anything else, they're equal too.
Exterior AngleAn angle supplementary to one of the triangle's inner angles. Just extend one of the sides of the triangle, and you'll see what we mean.
Exterior Angle TheoremThe measure of an exterior angle is equal to the sum of the measures of the remote interior angles. Even though it's an exterior theorem, you can use it indoors.
Hypotenuse-Leg TheoremIf the hypotenuses and corresponding legs of two right triangles are congruent, the two triangles are congruent. They've both gotta be right triangles though, or the deal's off.
Interior AngleOne of the inside angles in a triangle. They're innies, not outies.
Isosceles TriangleA triangle with at least two congruent sides (or, from the Isosceles Triangle Theorem, two congruent angles).
Isosceles Triangle TheoremTwo sides of a triangle are congruent to each other only if the angles opposite the sides are congruent to each other. The sides and angles can go on double-dates.
Obtuse TriangleA triangle that's a little slow on the uptake. Or one with an angle that's over 90°.
Remote Interior AnglesTwo of a triangle's interior angles that aren't supplementary to a given exterior angle.
Right TriangleA triangle that has an angle that's exactly 90°. Or possibly a triangle that's just never wrong about anything.
Scalene TriangleA triangle whose three sides are all different lengths. He's probably just going through a growth spurt.
SAS PostulateIf two corresponding sides and the angle between the sides in any two triangles are congruent, the two triangles are congruent.
SSS PostulateIf all three sides in any two triangles are congruent, the two triangles are congruent. This is what gives triangles their rigid structure (but it won't make them any more emotionally stable).
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