A maths formula 1st half

Surds :
Logarithms : log a y = x means ax =y
S
A log a m + log a n = log a (m x n)
log a m - log a n = log a
C
T log a mn = n log a m
log a 1 = 0
log a a = 1
log a b =

a
Sin a

Cos a

Tan a

1
Sin (-x) = - sin x
Cos (-x) = cos x
Tan (-x) = - tan x


Cot = sec = cosec =
Important identities
Sin2x + cos2x = 1
1+ cot 2 x = cosec 2 x
1 + tan 2 x = sec 2 x
Sin ( 90 – x) = Cos x
Cos (90 – x) = Sin x

Sum & difference of 2 angles
Sin (a +/- b) = Sin a Cos b +/- Cos a Sin b
Cos ( a +/- b ) = Cos a Cos b -/+ Sin a Sin b
Tan (a +/- b) =

Multiple angles
Sin 2A = 2 cos A sin A
Cos 2A = Cos2A – Sin2A
= 2Cos2A – 1
= 1 – 2Sin2A
Tan 2A =

Factor formula
Sin x + sin Y = 2 sin cos
Sin X – Sin Y = 2 cos sin
Cos X + Cos Y = 2 cos cos
Cos X – Cos Y = -2sin sin

ÿ©™
26/3/2008
09:23 PM
©™ :Yew Cheng