Question

If A=2B=60^(@) find the value of cos A+sin B​

Answer 1

Answer:

sin(A + 2B) = √3/2

sin(A + 2B) = sin 60°

⇒ A + 2B = 60° -----(1)

also given that,

cos(A + 4B) = 0

cos(A + 4B) = cos 90°

⇒ A + 4B = 90° -----(2)

Subtracting (1) from (2), we get

A + 4B - A - 2B = 90° - 60°

2B = 30°

⇒ B = 15°

Putting B = 15° in eq (1), we get

A + 2 (15°) = 60°

A + 30° = 60°

⇒ A = 30°

apply this method

Answer 2

Answer:

$if \: a = 2b = 60 \\ 2b = 60 \\ b = 30 \\ then \: \cos(a) + \sin(b) \\ \cos(60) + \sin(30) = \frac{1}{2} + \frac{1}{2} = 1$