∫((du)/((a^2) + (u^2))
(1/a) arctan(u/a) + C
Trig identities
tanx = sinx/cosx, sin^2x + cos^2x = 1, tan^2x = sec^2x -1, 1+cot²x = csc²x
sin2x = …
2sinxcosx
cos2x = ….
cos²x-sin²x OR 1-2sin²x OR 2cos²x - 1
cos²x = ….
(1+cos2x)/2
sin²x = …..
(1-cos2x)/2
if there are odd numbers of a trig function, do what?
save 1 and substitute the even for a trig identity
for even powers of sin and cos, use what?
half angle identities
if sec^n x, n is even and greater than 0, do what…
pull 2 off and save them, replace with trig identity.
if both tan and sec are odd, do what…
save a tanxsecx, tan has to have an odd power for this to work.
trig substitution is done when… (also list the 3 rules)
you are integrating the square root of a quadratic function
sqrt(a² - x²) → x =asinθ
sqrt(x² - a²) → x =asecθ
sqrt(x²+a²) → x=atanθ
even functions
functions that are symmetrical to the y-axis (odd x even = odd, even x even = even, odd x odd = even)
odd functions
functions that are symmetrical to the origin (0,0)