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Question

Question: If n is any integer, then the general solution of the equation \(R_{1}\) is....

If n is any integer, then the general solution of the equation R1R_{1} is.

A

4sin4θ=24\sin 4\theta = - 2 or sin4θ=12\sin 4\theta = \frac{- 1}{2}

B

4θ=7π64\theta = \frac{7\pi}{6}

C

11π6\frac{11\pi}{6} or 0<4θ<2π0 < 4\theta < 2\pi

D

\therefore or 0<θ<π20 < \theta < \frac{\pi}{2}

Answer

11π6\frac{11\pi}{6} or 0<4θ<2π0 < 4\theta < 2\pi

Explanation

Solution

Given equation is,1tanA2tanB2=cosA2cosB2sinA2sinB2cosA2cosB21 - \tan\frac{A}{2}\tan\frac{B}{2} = \frac{\cos\frac{A}{2}\cos\frac{B}{2} - \sin\frac{A}{2}\sin\frac{B}{2}}{\cos\frac{A}{2}\cos\frac{B}{2}}

Dividing equation by =cos(A2+B2)cosA2cosB2=sinC2cosA2cosB2= \frac{\cos\left( \frac{A}{2} + \frac{B}{2} \right)}{\cos\frac{A}{2}\cos\frac{B}{2}} = \frac{\sin\frac{C}{2}}{\cos\frac{A}{2}\cos\frac{B}{2}},

b2cos2Aa2cos2Bb^{2}\cos 2A - a^{2}\cos 2B

=b2(12sin2A)a2(12sin2B)= b^{2}(1 - 2\sin^{2}A) - a^{2}(1 - 2\sin^{2}B). Hence, =b2a22(b2sin2Aa2sin2B)=b2a2= b^{2} - a^{2} - 2(b^{2}\sin^{2}A - a^{2}\sin^{2}B) = b^{2} - a^{2}

asin(BC)+bsin(CA)+csin(AB)a\sin(B - C) + b\sin(C - A) + c\sin(A - B)

or=k(ΣsinAsin(BC)= k(\Sigma\sin A\sin(B - C).