Similar polygons

Today we learned more about similar shapes. We reviewed the rules for telling weather two polygons are similar, which were equal angles, proportional sides, and the same basic shape. Finally, we learned how to find the angle measures and side lengths of one triangle, using it's similar shape. The picture to the left shows two similar triangles, UVY and XYZ. As you can see, all three of the corresponding angles are marked with the same number of arcs, which means that they are equal to eachother. The sides are also proplotinal to eachother. The scale factor of XYZ to UVW is two. This means that the are of XYZ is four times as large as the area of UVW. Finally, you can tell that they are similar because of their basic shape. This is one important rule used to find out if two shapes are similar.

Stretching & Shrinking Problem 3.3 wrap up

Stretching & Shrinking Wrap Up 3.3, Intro Mr Rr

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Stretching & Shrinking Problem 3.3

Stretching & Shrinking Problem 3.3 Rr

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Lesson 3.2

Today in class we learned about how to use rep-tile triangles to construct larger similar triangles. A rep-tile in math is any shape that, in a group with identical shapes can fit to gather to make a larger version of the shape. For example, a square is a rep-tile because if you fit four squares together it creates a larger square. An example for a non-rep-tile is a hexagon because no matter how many hexagons you fit together you can't create a larger hexagon. So today we split up into groups and each group recieved a bag of pattern-block triangles. Each group received a bag of either, isosceles, scalene, or right tringles. Then, each group would have to figure out how to use the given triangles to create a larger version of their triangles. We would use the information we found to answer questions in the "Stretching and Shrinking" book section 3.2 Afterwards, as a class we reviewed our answers and learned that all triangles are rep-tiles.

Stretching & Shrinking Reptile Triangles

Stretching & Shrinking 3.2 Wrap Up Rectangles

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Problem 3.1

In class today we learned about how larger shapes are similar to the original shape. For example If the original shape was a parallelogram the first lager similar shape would be 4 times larger than the original shape, 4 units would have been used and the scale factor would be 2. A good thing to remember is that in similar shapes the side lengths and perimeter change by the scale factor. Area of the original times the scale factor squared gives the area of the new shape. The definition of scale factor is the number used to multiply the lengths of a figure to stretch or shrink it to a similar image. For example if the scale factor was 3 all the lengths of the new image would be 3 times larger than the original image.

By Nicole Doherty

Stretching & Shrinking Problem 3.1 wrap up

Wrap Up 3.1 Intro 3.2 Rr

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