Mathematics
If 2 cos (A + B) = 2 sin (A - B) = 1; find the values of A and B.
Trigonometric Identities
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Answer
2 cos (A + B) = 1
⇒ cos (A + B) =
⇒ cos (A + B) = cos 60°
So, A + B = 60° ……………(1)
2 sin (A - B) = 1
⇒ sin (A - B) =
⇒ sin (A - B) = sin 30°
So, A - B = 30° ……………(2)
Adding equation (1) and (2), we get
(A + B) + (A - B) = 60° + 30°
⇒ A + B + A - B = 90°
⇒ 2A = 90°
⇒ A =
⇒ A = 45°
From equation (2), A - B = 30°
⇒ 45° - B = 30°
⇒ B = 45° - 30°
⇒ B = 15°
Hence, A = 45° and B = 15°.
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