Mathematics

geometric shapes (plane figures)

World Encyclopedia | 2005 | Copyright

geometric shapes (plane figures)

Types of triangle
Equilateral	All the sides are the same length and all the angles are equal.
Isosceles	Two sides are of the same length and two angles are of equal size.
Scalene	All sides are different lengths and all the angles are of different sizes.
Acute angle	A triangle with three acute angles, each less than 90°.
Right angle	A triangle containing one right angle (90°).
Obtuse angle	A triangle containing one obtuse angle (over 90°).

Types of quadrilateral
Square	All the sides are the same length and all the angles are right angles.
Rectangle	Opposite sides are the same length and all angles are right angles.
Rhombus	All sides are the same length but none of the angles are right ngles.
Parallelogram	Opposite sides are parallel to each other and of the same length.
Trapezium	One pair of the opposite sides is parallel.
Kite	Adjacent sides are equal length and the diagonals intersect at right angles.

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World Encyclopedia | 2005 | Copyright

geometric figures

Pythagoras' theorem: a2 = b2+c2
¹ = 3.1415926 (recurring) r = radius
Shape	Circumference	Area
circle	2¹r	¹r2
Parallelogram (l = length, h = perpendicular distance to side parallel to l)	lh
Rectangle (l = length, w = width)	lw
triangle		1/2lh
Shape	Volume	Surface area
Cone (h = perpendicular height)	1/3¹r2h	¹r2+¹rl
cylinder	¹r2h	¹r2+2¹rh
Pyramid (B = area of base)	1/3Bh
sphere	4/3¹r3	4¹r2

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"geometric figures." World Encyclopedia. 2005. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>.

"geometric figures." World Encyclopedia. 2005. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O142-geometricfigures.html

"geometric figures." World Encyclopedia. 2005. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-geometricfigures.html

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