Solve this : Q u e s t i o n N o . 10 I n △ A B C , i f sin 2 A - sin 2 B = 2 3 a n d cos 2 A + cos 2 B = 4 3 , t h e n w h a t i s t h e v a l u e o f cos 2 C ? A . 4 9 B . 5 9 C . 8 9 D . 1 9 Share with your friends Share 0 Aarushi Mishra answered this sin 2A-sin 2B=23Squaring both sidessin2 2A+sin2 2B-2 sin 2A sin 2B=49 ________________1cos 2A+cos 2B=43Squaring both sidescos2 2A+cos2 2B+2 cos 2A cos2B=169 ________________2Adding equation 1 and 2sin2 2A+sin2 2B-2 sin 2A sin 2B+cos2 2A+cos2 2B+2 cos 2A cos2B=49+169sin2 2A+cos2 2A+sin2 2B+cos2 2B+2 cos 2A cos2B-sin 2A sin 2B=209Use sin2x+cos2y=1 and cosx cosy-sinx sin y=cos x+y1+1+2 cos 2A+2B=2092 cos 2A+B=209-2=29cos 2A+B=19cos 2π-C=19cos 2C=19Use cos 2x=2cos2x-12cos2C-1=192cos2C=19+1=109cos2C=59 0 View Full Answer Bhavya Choudhary answered this Which app is this? 0 Pallavi answered this whats this ? 0