general solution (1 Viewer)

[1234567]

write down the general solution of the equation cos3x=cospi/5

 

[BlackJack]

???
Is it x= 2/3 n pi +- pi/15? (check ppl, I'm not studying maths at the moment, my english is bad enough)

 

[1234567]

how do u work it out.....

 

[BlackJack]

We've got textbook that has the general solutions. Try to remember these:

For sin x = sin a
x= npi + (-1)^n * a

For cos x = cos a
x = 2npi +- a

For tanx = tan a
x= npi + a

There are explanations if you want them, but look at the graphs of the functions and try to work it out from there...

 

[Dumbarse]

so did u just do

cos3x=cospi/5

so 3x = 2npi +/- pi/5

.'. x = 2/3npi +/- pi/15
??

 

[1234567]

think that's what he did.

 

[BlackJack]

yeah.

 

[Dumbarse]

is that right?