## geometric shapes (plane figures)

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°).

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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## geometric figures

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