Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2007-08-03 04:31:11

tony123
Member
Registered: 2007-08-03
Posts: 228

how

please some one tell me how


integral ∫1/(4 + 5 ( cos x )^2 ) dx= (1/6)tan-¹[(2tanx)/3] + c
dunno

Offline

#2 2007-08-03 07:37:50

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

Re: how

Well, since you are given the answer, why not work backwards from the answer and see if we get somewhere? big_smile

I differentiated the answer for some ideas and this is what I came up with.

Now use the subsitution u = (2⁄3)tanx. This will transform the integral to

which is

Offline

Board footer

Powered by FluxBB