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If sin(x-y)=cos(x+y)=1/2, the value of x...

If `sin(x-y)=cos(x+y)=1/2,` the value of x and y lyingbetween `0^(@)and 90^(@)` are given by

A

`x=15^(@),y=25^(@)`

B

`x=65^(@),y=15^(@)`

C

`x=45^(@),y=45^(@)`

D

`x=45^(@),y=15^(@)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the values of \( x \) and \( y \) given that: \[ \sin(x - y) = \frac{1}{2} \quad \text{and} \quad \cos(x + y) = \frac{1}{2} \] ### Step 1: Solve for \( x - y \) From the equation \( \sin(x - y) = \frac{1}{2} \), we know that: \[ x - y = 30^\circ \quad \text{or} \quad x - y = 150^\circ \] However, since \( x \) and \( y \) are both between \( 0^\circ \) and \( 90^\circ \), we will only consider: \[ x - y = 30^\circ \quad \text{(Equation 1)} \] ### Step 2: Solve for \( x + y \) From the equation \( \cos(x + y) = \frac{1}{2} \), we know that: \[ x + y = 60^\circ \quad \text{or} \quad x + y = 300^\circ \] Again, since \( x \) and \( y \) are both between \( 0^\circ \) and \( 90^\circ \), we will only consider: \[ x + y = 60^\circ \quad \text{(Equation 2)} \] ### Step 3: Add Equation 1 and Equation 2 Now, we can add Equation 1 and Equation 2: \[ (x - y) + (x + y) = 30^\circ + 60^\circ \] This simplifies to: \[ 2x = 90^\circ \] Dividing both sides by 2 gives: \[ x = 45^\circ \] ### Step 4: Substitute \( x \) back to find \( y \) Now, we can substitute \( x = 45^\circ \) back into Equation 1 to find \( y \): \[ 45^\circ - y = 30^\circ \] Solving for \( y \): \[ y = 45^\circ - 30^\circ = 15^\circ \] ### Conclusion Thus, the values of \( x \) and \( y \) are: \[ x = 45^\circ, \quad y = 15^\circ \] ### Final Answer The correct option is \( x = 45^\circ \) and \( y = 15^\circ \). ---
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