Question

Cos3a-cosa ——————— cos3a+cosa

Answer 1

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Answer 2

Вроде так

tg2a=2tga/(1-rg^2x)

Можешь подставить, если захочешь

Answer 3

To simplify the expression (cos(3a) - cos(a)) / (cos(3a) + cos(a)), we can use the trigonometric identity for the difference of cubes:

cos(3a) - cos(a) = (cos(a))^3 - (cos(3a))^3 = (cos(a) - cos(3a))(cos(a)^2 + cos(a)cos(3a) + (cos(3a))^2).

Substituting this back into the original expression:

[(cos(a) - cos(3a))(cos(a)^2 + cos(a)cos(3a) + (cos(3a))^2)] / (cos(3a) + cos(a)).

Now, notice that the terms (cos(a) - cos(3a)) cancel out in the numerator and denominator, leaving:

(cos(a)^2 + cos(a)cos(3a) + (cos(3a))^2) / (cos(3a) + cos(a)).

At this point, we can factor out a common factor of cos(a) in the numerator:

cos(a)(cos(a) + cos(3a) + (cos(3a))^2) / (cos(3a) + cos(a)).

Finally, we can simplify further by canceling out the common factor of (cos(3a) + cos(a)) in the numerator and denominator:

cos(a).

Therefore, the simplified expression is cos(a).