If  and   find A and B[CBSE 2008, 2009]

Now, we know that 



So, from the question we can tell,

tan (A + B) =

tan (A + B) = tan 60^o

A + B = 60°                  .......eq (i)

tan (A – B) =

tan (A - B) = tan 30°

A - B = 30                 ...........eq(ii)

On adding both equations, we obtain

2 A = 90°

⇒ A = 45

From equation (i), we obtain

45 + B = 60

B = 15^o

Therefore, ∠A = 45° and ∠B = 15°