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If cos (x + y) = 12\frac{1}{2}21​ and sin (x - y) = 0, where x and y are positive acute angle and x≥yx \geq yx≥y, then x and y are :​
Question

If cos (x + y) = 12\frac{1}{2} and sin (x - y) = 0, where x and y are positive acute angle and xyx \geq y, then x and y are :​

A.

80o80^o and 80o80^o​​

B.

60o60^o and 60o60^o​​

C.

45o45^o  and 45o45^o​​

D.

30o30^o and 30o30^o​​

Correct option is D

Given:

cos(x+y)=12cos(x + y) = \frac{1}{2} 

sin(xy)=0sin(x - y) = 0 

where x and y are positive acute angle and x ≥ y,  

Formula Used: 

cos600=12 sin00=0\cos 60^0 = \frac{1}{2} \\ \ \\ \sin 0^0 = 0 

Solution:

cos(x+y)=12cos(x + y) = \frac{1}{2} 

cos( x + y ) = cos 60°

x + y = 60° ......(1)

Or sin(x - y ) = 0 

sin ( x - y) = sin 0° 

x  - y = 0°.......(2) 

Solving eq. 1 and 2 we get; 

x = y = 30°

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