Question

How can i simplify this
cos(-pi + x)cot(pi/2 - x)

Answer 1

@dan815 Hey buddy! Wanna help? ^_^

Answer 2

use property cos(-x)=cos x

Answer 3

Doesnt it = -cos(x)?

Answer 4

no cos is postive on I and IV quadrants ..inact cos is an even function

Answer 5

Did i mistake it for sin? or is sin the same also

Answer 6

sin(-u)= -sin(u) Odd
cos(-u)= cos(u) Even
tan(-u)= -tan(u) Odd
sec(-u)= sec(u) Even
csc(-u)= -csc(u) Odd
cot(-u)= -cot(u) Odd
where u=any real number

You just have to memorize these

Answer 7

Oh man buddy thanks i really needed that! ^_^

Answer 8

yw :)

Answer 9

so back to the question...

Answer 10

i cant quite get the cot(pi/2) part down

Answer 11

this is what defines odd function
-f(x)=f(x) like x
even = f(-x)=f(x) like x^2

Answer 12

it is tan x :)

Answer 13

cot(pi/2 - x)=tan x

Answer 14

hmmmm wait why is that?

Answer 15

OH! 90degrees - x is cofunction

Answer 16

just study these thoroughly

http://www.mathwords.com/t/trig_identities.htm

Answer 17

you can answer all these qns easily

Answer 18

Okay thanks! I understand now! ^_^ I will study those

Answer 19

yw :)

Answer 20

Thanks @dan815 also :P