Shape Stretcher

Pre-Algebra · Axiom Academy

Stretch and shrink a shape by a scale factor, and watch what stays the same. The big idea hiding inside: similar figures. One factor stretches everything at once Resizing a photo, reading a map, zooming on your phone — every one of these grows or shrinks a shape without bending it out of form. The secret is a single number, the scale factor, that multiplies every length by the same amount. Watch this right triangle grow. Press play and the scale factor k climbs from 1; the figure enlarges, and the three side labels (3, 4, 5) all stretch together — each one becoming its original length times k. Same shape, bigger size — because one factor stretched every side by the same amount. Drive the scale factor — every side keeps in step Drag the scale factor. The blue original holds still while the green copy stretches and shrinks. Read the side labels: at every setting, each green side is its blue side times k. Divide any green side by its blue partner and you always get back k — that's what "proportional" means. One slider, every length — base, height, and hypotenuse all multiply by k together. Sides change — but the angles don't budge Both triangles share the bottom-left corner. Crank the scale factor and the green sides slide outward, but the corner angles stay pinned exactly on top of the originals. Same angles, sides scaled by one factor — that is precisely what makes two figures similar . The angles read the same at every scale factor — only the sizes of the sides change.

This is the written version of the interactive lesson above. See the full Pre-Algebra course.