easy angle thing

[red and white kop!]

ok so i have this list of question like this one:
find the least positive value of B for which sin(A-B)=cos(A+B)

using translation, odd, periodic properties, etc.
the problem is i totally forgot how to work these out! i know there is a simple method to work this out without staring continually at the sin and cos graphs, i just need a little reminder. thanks

 

[Deleted member 4993]

ok so i have this list of question like this one:
find the least positive value of B for which sin(A-B)=cos(A+B)

using translation, odd, periodic properties, etc.
the problem is i totally forgot how to work these out! i know there is a simple method to work this out without staring continually at the sin and cos graphs, i just need a little reminder. thanks

For the problem you posted, it seems that angle A has to have a least positive value (not B).

sin(A-B)=cos(A+B)

cos(?/2 - A + B) = cos(A + B)

?/2 - A = A

A = ?/4

 

[red and white kop!]

thanks