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Basic 2D Geometry

Although they may already be familiar, it is important to be sure you know the basic geometric shapes:

円形 – えんけい – a circle
三角形 – さんかくけい – a triangle
正方形 – せいほうけい – a square
四角形 – しかくけい – a quadrilateral
長方形 – ちょうほうけい – a rectangle
五角形 – ごかくけい – a pentagon
六角形 – ろっかくけい – a hexagon
七角形 – しちかくけい – a septagon/heptagon
八角形 – はっかくけい – an octagon

In these words, 「かくけい」 can alternatively be pronounced 「かっけい」, which is a little easier to pronounce.

Equilateral shapes are prefixed with 「正 – せい」.

正三角形 – せいさんかくけい – equilateral triangle
正六角形 – せいろっかくけい – equilateral hexagon

There are several specific triangles and quadrilateral with specific terminology:
二等辺三角形 – にとうへんさんかくけい – isoceles triangle
直角三角形 – ちょっかくさんかくけい – right triangle (「直角 – ちょっかく」is right angle)
直角二等辺三角 – ちょっかくにとうへんさんかくけい – isoceles right triangle

黄金四角形 – おうごんしかくけい – golden rectangle
台形 – だいけい – trapezoid
平行四辺形 – へいこうしへんけい – a parallelogram
菱形 – ひしがた – a rhombus
凧型 – たこがた – kite shape

Of course, there are a variety of other two dimensional figures, some of which I will list here:

楕円 – だえん – ellipse
五芒星 – ごぼうせい – pentagram
六芒星 – ろくぼうせい – six pointed star/star of david
ハート形 – はーとがた – heart shape

Not shapes, but two dimensional lines:
双曲線 – そうきょくせん – hyperbola
放物線 – ほうぶつせん – parabola

There are many other shapes, but I think this covers the basic geometric shapes of particular mathematical significance fairly well.

This entry was posted on Tuesday, October 5th, 2010 at 1:34 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.

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