If sin (A + B) = cos (A – B) = √3/2, find A and B.

1.	If sin (A + B) = cos (A – B) = √3/2, find A and B.
Answer» Given : sin(A + B) = √3/2 ⇒ Sin(A+B) = sin (60^o) [sin(60^o) = √3/2] On equating both the sides, we get A + B = 60^o …(1) And cos(A - B) = √3/2 ⇒ cos(A – B) = cos (30^o) [cos(30^o) = √3/2] On equating both the sides, we get A – B = 30^o …(2) On Adding Eq. (1) and (2), we get 2A = 90^o ⇒ A = 45^o Now, Putting the value of A in Eq.(1), we get 45^o + B = 60^o ⇒ B = 15^o Hence, A = 45^o and B = 15^o

Answer»

Given : sin(A + B) = √3/2

⇒ Sin(A+B) = sin (60^o) [sin(60^o) = √3/2]

On equating both the sides, we get

A + B = 60^o …(1)

And cos(A - B) = √3/2

⇒ cos(A – B) = cos (30^o) [cos(30^o) = √3/2]

On equating both the sides, we get

A – B = 30^o …(2)

On Adding Eq. (1) and (2), we get

2A = 90^o

⇒ A = 45^o

Now, Putting the value of A in Eq.(1), we get

45^o + B = 60^o

⇒ B = 15^o

Hence, A = 45^o and B = 15^o

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