Question

29. cos(x + 2) + cosx + cos(x+20) - cos3x. 3 4

JEE/Engineering Exams

Maths

Solution

147

4.0 (1 ratings)

( cos ^{3}left(x-frac{2 pi}{3}right)+cos ^{3} x+cos ^{3}(x+2 pi / 3)=frac{3 cos 3 x}{4} ) ( V sin g cos 3 x=4 cos 3 x-3 cos x ) ( cos ^{3} x=frac{cos 3 x+3 cos x}{4} ) Sulstituting in LHS

29. cos(x + 2) + cos*x + cos*(x+20) - cos3x. 3 4

29. cos(x + 2) + cosx + cos(x+20) - cos3x. 3 4