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area of sector (where θ is in radians)
½r²θ
angles in 3d vectors
cosθₓ =x/|a|
cosθᵧ =y/|a|
cosθ₂ =z/|a|
this is where vector a makes an angle θ with the x/y/z axis (because x/y/z would be the
adjacent and a the hypotenuse)
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expanding (a + bx)ⁿ
(a + bx)ⁿ = aⁿ(1 + (b/a)x)ⁿ
cosine rule
, a² = b² +c² -2bc cosa
rule for parametric integration
∫y dx = ∫(y dx/dt)dt
as (dx/dt) x dt would cancel out to give you ∫y dx
unit vector (â)
a / |a|
vector / magnitude of vector
rule for implicit differentiation of terms with xy
d/dx (xy) = x dy/dx + y
(basically use the product rule then times the x-term by dy/dx)
e.g. d/dx (3xy) = 3x x 1(dy/dx) + 3y
= 3x(dy/dx) + 3y
arc length