5x - sin 3x)
sin 5x + sin 3x
7.
tan 4x
cos 5 x + cos 3x
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Answer: LHS = (sin5x + sin3x)/(cos5x + cos3x)
use the formula,
sinC + sinD = 2sin(C + D)/2.cos(C-D)/2
cosC + cosD = 2cos(C + D)/2.cos(C - D)/2
= {2sin(5x+3x)/2.cos(5x-3x)/2}/{2cos(5x+3x)/2.cos(5x-3x)/2}
= (2sin4x.cosx)/(2cos4x.cosx)
= sin4x/cos4x
= tan4x = RHS
Step-by-step explanation:
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