inverse trig integration (1 Viewer)

[fashionista]

hi!!! i did this question today...but seeing as there are no answers to check it against i was hoping someone could help me out so i can see if i got it right.....yess yess i know i'm on a question asking rampage but it'll all be over after tonight..after this one infact..i think
so here it is

integral of (2inverse tan(3x)) with limits pi/2 and -pi/2

thanking you muchly

p.s. i did it by parts

 

[wogboy]

integral of (2inverse tan(3x)) with limits pi/2 and -pi/2

That integral is just 0, are you sure you haven't made a typo? If you integrate any odd function from -a to a (for any value of a) then you get zero, inverse tan is an odd function.

 

[kimmeh]

Originally posted by fashionista
p.s. i did it by parts

you shouldnt be using 4 unit methods for 3 unit exams

Yes, i agree with wogboy, its an odd function.

 

[:: ck ::]

if u get asked to integrate like inverse tan x in 3unit exam

dont bother doing 4unit by parts

just change it to like x = tany

integrate from that...

usually u use a small trick like area of a rectangle ... minus the area between curve and y axis if the question was the find the area between curve and x axis....

 

[fashionista]

omg are u serious??? it's zero?? THANK U!!!! i thought i was completely wrong when i got that answer. yeah i know i shouldnt be using 4 unit in 3unit but i couldnt think of how to do it the 3 u way. i hope they dont get angry at me for that. but thanku!! im so happy atleast i got it right.

 

[kpq_sniper017]

it seems ironic in a way that 3U students actually have to think of a method of solving it, and yet 4U students can use integration by parts, which is probably easier...
btw. i don't know if it is coz i haven't started 4U yet.