![]() Cut the other length into two distinctly unequal parts. You can replicate the SSS Postulate using two straight objects – uncooked spaghetti or plastic stirrers work great.Ĭut a tiny bit off one, so it is not quite as long as it started out. This is the only postulate that does not deal with angles. Perhaps the easiest of the three postulates, Side Side Side Postulate (SSS) says triangles are congruent if three sides of one triangle are congruent to the corresponding sides of the other triangle. ![]() Or the two triangles to be congruent, those three parts – a side, included angle, and adjacent side – must be congruent to the same three parts – the corresponding side, angle and side – on the other triangle, △YAK. Move to the next side (in whichever direction you want to move), which will sweep up an included angle. ![]() Notice we are not forcing you to pick a particular side, because we know this works no matter where you start. The SAS Postulate says that triangles are congruent if any pair of corresponding sides and their included angle are congruent. Here, instead of picking two angles, we pick a side and its corresponding side on two triangles. SAS theorem (Side-Angle-Side)īy applying the Side Angle Side Postulate (SAS), you can also be sure your two triangles are congruent. You will see that all the angles and all the sides are congruent in the two triangles, no matter which ones you pick to compare. So go ahead look at either ∠C and ∠T or ∠A and ∠T on △CAT.Ĭompare them to the corresponding angles on △BUG. The postulate says you can pick any two angles and their included side. You may think we rigged this, because we forced you to look at particular angles. You can only make one triangle (or its reflection) with given sides and angles. This is because interior angles of triangles add to 180°. Transformations, and there are rules that transformations follow in coordinate geometry.180 ° − ∠ C − ∠ A 180°-\angle C-\angle A 180° − ∠ C − ∠ A In summary, a geometric transformation is how a shape moves on a plane or grid. If you have an isosceles triangle preimage with legs of 9 feet, and you apply a scale factor of 2 3 \frac 3 2 , the image will have legs of 6 feet. Mathematically, a shear looks like this, where m is the shear factor you wish to apply:ĭilating a polygon means repeating the original angles of a polygon and multiplying or dividing every side by a scale factor. Italic letters on a computer are examples of shear. Shearing a figure means fixing one line of the polygon and moving all the other points and lines in a particular direction, in proportion to their distance from the given, fixed-line. If the figure has a vertex at (-5, 4) and you are using the y-axis as the line of reflection, then the reflected vertex will be at (5, 4). Reflecting a polygon across a line of reflection means counting the distance of each vertex to the line, then counting that same distance away from the line in the other direction. To rotate 270°: (x, y)→ (y, −x) (multiply the x-value times -1 and switch the x- and y-values) To rotate 180°: (x, y)→(−x, −y) make(multiply both the y-value and x-value times -1) To rotate 90°: (x, y)→(−y, x) (multiply the y-value times -1 and switch the x- and y-values) Rotation using the coordinate grid is similarly easy using the x-axis and y-axis:
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