Geometry 400 FORMULAS
Terms
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 Midpoint
 C1+C2/2
 Number of triangles in a polygon
 n  2
 Sum of interior angles of a regular polygon
 180(n  2)
 Measure of exterior andles of a regular polygon
 360/n
 Measure of interior angles of a regular polygon
 s/n
 Number of diagonals from any vertex in a regular polygon
 n  3
 Total number of diagonals
 n(n  3)/2
 Proportion

P.O.M. = P.O.E.
a/b = c/d  Measure of a median of a triangle
 1/2 base
 distance formula

the square root of
(x  x)2 + (y  y)2  sine ()
 opposite side / hypotenuse
 cosine
 adjacent side / hypotenuse
 tangent
 opposite side / adjacent side
 measure of a central angle
 = measure of intercepted arc
 measure of an inscribed angle
 = 1/2 measure of intercepted arc
 measure of an interior angle
 = 1/2 sum of two intercepted arcs
 measure of an exterior angle
 = 1/2 difference of intercepted arcs
 when a tangent segment intersects a secant segment...
 tangent segment2 = outside times the whole thing.
 when two secant segments intersect outside the circle....
 the outside times the whole thing = the outside times the whole thing.
 lateral area of a prism
 perimeter of base x height
 lateral area of a cylinder
 2(pi)rh
 total area of a prism and cylinder
 lateral area + 2 (base area)
 volulme of a prism
 base area x height
 volume of a cylinder
 (pi)r2h
 lateral area of a pyramid
 slant height (perimeter) / 2
 lateral area of a cone
 (pi)r x slant height
 total area of a cone and pyramid
 lateral area + base area
 area of a sphere
 4(pi)r2
 volume of a sphere
 4(pi)r3/3
 # of faces
 s + 2
 # of verticies
 2s
 # edges
 3s
 perimeter of a polygon
 sum of sides
 circumference of a circle
 (pi)d
 length of an arc
 m. of arc x circumference/360
 area of a parallelogram
 bh
 area of a rhombus, square, kite
 d x d/2
 area of a triangle
 bh/2
 area of a triangle (w/ semiperimeter)

square root of
s(sa)(sb)(sc)  area of an equilateral triangle
 s2 / 4 (square root of 3)
 area of a trapezoid
 (b + b)h/2
 area of a circle
 (pi)r2
 area of a regular polygon
 ap/2
 area of a sector
 m. of arc x area of circle / 360
 area of a segment
 area of a sector  area of a triangle
 area of a triangle (w. sine)
 1/2ab sine c