Turn on thread page Beta
 You are Here: Home

# P3 Integration watch

1. Please can someone help me with this question?

I know it should be simple but I can't get the answer
Attached Images

2. (Original post by Pixelfairy #1)
Please can someone help me with this question?
xtanx - integral of tanx

xtanx -ln sec x

xtan x - ln (1/cos)

pie / 4 - 1/2 ln 2
3. (Original post by tammypotato)
xtanx - integral of tanx

xtanx -ln sec x

xtan x - ln (1/cos)

pie / 4 - 1/2 ln 2
Thanks... lol i shouldnt of bothered posting it
4. (Original post by Pixelfairy #1)
Thanks... lol i shouldnt of bothered posting it
yeah lol
5. (Original post by tammypotato)
yeah lol
In all fairness I did post it before you told me how to do it
6. (Original post by Pixelfairy #1)
In all fairness I did post it before you told me how to do it
how does INT of xtanx become lnsecx?? do i just have to know that, or is there a way of showing it?
7. (Original post by wonkey)
how does INT of xtanx become lnsecx?? do i just have to know that, or is there a way of showing it?
The integral of tan x = ln |sec x|

INT tan x dx = INT sin x dx/cos x

u = cos x, du = -sin x dx

INT -du/u = -ln u + C

=> -ln |cos x| + C

Using log law nln a = ln a^n:

ln |(cos x)^-1| + C = ln |sec x| + C
8. (Original post by Nylex)
The integral of tan x = ln |sec x|

INT tan x dx = INT sin x dx/cos x

u = cos x, du = -sin x dx

INT -du/u = -ln u + C

=> -ln |cos x| + C

Using log law nln a = ln a^n:

ln |(cos x)^-1| + C = ln |sec x| + C
thx so much....i just had in my head that INT of tanx = -lncos x
9. (Original post by Nylex)
The integral of tan x = ln |sec x|

INT tan x dx = INT sin x dx/cos x

u = cos x, du = -sin x dx

INT -du/u = -ln u + C

=> -ln |cos x| + C

Using log law nln a = ln a^n:

ln |(cos x)^-1| + C = ln |sec x| + C
was i right tho?
10. (Original post by tammypotato)
was i right tho?

yes
11. same answer but typed up
Attached Images
12. trig p3.pdf (9.2 KB, 279 views)

Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 7, 2004
Today on TSR

### Edexcel C3 Maths Unofficial Markscheme

Find out how you've done here

### Should predicted grades be ditched

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.