FIND

Asked by  | 27th Aug, 2008, 09:07: PM

Expert Answer:

we can write 2a= (a+b)+(a-b) and 2b = (a+b)-(a-b)

tan(2a) =tan( (a+b)+(a-b) ) = (tan(a+b) +tan(a-b) ) / ( 1-tan(a+b) tan(a-b)) =  (x+y) / (1-xy)

similarly tan(2b) =tan( (a+b)-(a-b) ) = (tan(a+b) - tan(a-b) ) / ( 1+ tan(a+b) tan(a-b)) =  (x-y) / (1+xy)

Answered by  | 8th Sep, 2008, 06:06: PM

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