Question

Find the general solution of cos 3x= -1/2

Answer 1

Heya

_______________________________

Cos 3x = Cos 120°

Becoz Cos 120° = -1/2

=>

3x = 120°

=>

x = 40°

So, it's general solution is

x = 2nπ ± 40

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Answer 2

The general solution of expression is $x=\frac{2n\pi\pm 120}{3}$

Step-by-step explanation:

Given : Expression $\cos 3x=-\frac{1}{2}$

To find : The general solution of expression ?

Solution :

$\cos 3x=-\frac{1}{2}$

The expression is also written as,

$\cos 3x=\cos 120^\circ$

The general solution of $\cos \theta=\cos \alpha$ where, $\alpha\in [0,\pi]$

$\theta=2n\pi\pm \alpha$

So, the solution is

$3x=2n\pi\pm 120$

$x=\frac{2n\pi\pm 120}{3}$

The general solution of expression is $x=\frac{2n\pi\pm 120}{3}$

#Learn more

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