Head First 2D Geometry

the index

perimeter of (see perimeter)

scaling (see scaling shapes)

similar (see similar shapes)

(see also specific shapes)

shooting example (see homicide example)

similar shapes, 58–63, 67, 77, 89, 100

proportional scaling of, 73–76

ratios for, 92–98

right triangles and, 120–122

(see also scaling shapes)

6-sided shapes (see hexagons)

skate ramp example, 104–147

multiple ramps, 132–135

perpendicular uprights, 106–131

rope swing, 139–147

sketches (see drawings)

speakers example, 170–180

spread angle of speakers, 170–172, 174

squares, 268

area of, 286

perimeter of, 286–287

similarity of, 77, 100

(see also quadrilaterals; regular polygons)

straight lines (see lines)

Super Triangles (Pythagorean triples), 146, 148

supplementary angles, 17–18, 47

T

3-sided shapes (see triangles)

3D shapes, volume of, 278–280

trapeziums, 270

trapezoids, 262, 267, 269, 272

area of, 260–265

bases of, 262

compared to parallelograms, 270

isosceles trapezoids, 267, 269

triangles

altitude line for, 144–145, 148

angles of, adding, 20–22, 46

angles of, estimating, 175–180

area of, 162–167, 202, 290–294

bisecting, 144–146

bounding rectangle for, 157–163

centers of, 181–188

equilateral triangles, 176, 188, 290–294, 318

hypotenuse of, 131, 138

isosceles triangles, 144–145, 175–180, 269

legs of, 131, 138, 141

medians of, 182, 202

perimeter of, 294

right triangles (see right triangles)

scalene triangles, 194–198

similar triangles, 58–63, 67, 73–76

V

vertical angles, 19, 40, 47

volume of 3D shapes, 278–280

Z

Z patterns, in parallel lines, 40, 47

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