3-1 The two conditions of similarity and the ratio of perimeters and areas
Point 1 of 11 — Unit 3: Similarity, Dilation, Trigonometric Ratios and the Straight LineQuestion bank: 0 questions (0 with pictures)
01 3-1 The two conditions of similarity and the ratio of perimeters and areas
Two polygons are similar when corresponding angles are equalandcorresponding sides are proportional — both at once.
The common ratio of corresponding sides is the scale factor k; k = 1 gives congruent figures.
Ratio of perimeters = k; ratio of areas = k². So from an area ratio take the square root to get k, and square k to get the area ratio.
Any two regular polygons with the same number of sides are similar; any two circles are similar; two rectangles or two rhombi are not necessarily similar.
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