Question

2(cosa +sinb) (cos a— sinb)
=cos2a +cos2b​

Answer 1

Step-by-step explanation:

l.h.s

2(cosa+sinb)(cosa_sinb)

2(cos2a-sin2b)

2(cosa2a-(1-cos2b)

2(cos2a-1-cos2b)

2-1(cos2a+cos2b)

cos2a+cos2b

l.hs=r.h.s