Question

How to get the right side ?

Answer 1

its easy, take inequality in use

Answer 2

there was once a famous quote..."one must go left to turn right"

Answer 3

I know how to get the left side but I am having a hard time to get the right one :)

Answer 4

this is proving yes?

Answer 5

no , i am trying to solve a fourier series of sawtooth function. and this bn coefficient

Answer 6

hmm interesting

Answer 7

i believe this is @hartnn 's specialty yes?

Answer 8

I am new i do not know nobody in here :(

Answer 9

speciality ? no.
M7, what is cos pi = ?

Answer 10

just have a look to this example in wikibidia http://en.wikipedia.org/wiki/Fourier_series

Answer 11

what is cos pi ?

Answer 12

cos pi ? it's -1 ..

Answer 13

and cos 2pi = ?

Answer 14

one

Answer 15

cos 3pi = ?

Answer 16

:) .. well what is your point ?

Answer 17

see the pattern ....
cos n*pi = ?

Answer 18

cos 1pi = -1
cos 2pi = 1
cos 3pi = -1
cos 4pi = 1

Answer 19

yeah i see it's 1,-1,1 and so on

Answer 20

so cos n*pi= ?

Answer 21

Under which topic in math can i find such examples ..

Answer 22

just use generalization :
cos n*pi = \(\huge (-1)^n\)

Answer 23

when i put 1, i get -1, when i put n=2, i get +1 and so o n

Answer 24

Awesome

Answer 25

and -cos (n*pi) = (-1)(-1)^n = ?

Answer 26

and i think sin n*pi will be easier for you to figure out

Answer 27

Hartnn thank you so much, you saved my life :)

Answer 28

welcome ^_^