Solve each trigonometric equation such that 0 ≤ x ≤ 2????. Round answers to three decimal places.
a. 5 cos(x) − 3 = 0
b. 3 cos(x) + 5 = 0
c. 3 sin(x) − 1 = 0
d. tan(x) = −0.115

Respuesta :

Answer:

a) [tex] x= arccos(3/5) = 0.927 [/tex]

Just one solution

b) [tex] cos(x) = -\frac{5}{3}[/tex]

But we know that the cosine can't be negative so then this equation no have solutions on the reals.

c) [tex] x = arcsin(\frac{1}{3})=0.3398[/tex]

This is only the solution on the interval assumed.

d) [tex] x= -0.1145[/tex]

Step-by-step explanation:

a. 5 cos(x) − 3 = 0

For this case we can do this:

[tex] 5 cos(x) = 3[/tex]

Now we can divide both sides by 5 and we got:

[tex] cos (x) = \frac{3}{5}[/tex]

If we apply arccos on both sides we got:

[tex] x = arccos (\frac{3}{5})+2\pi n, x=2\pi-arccos (\frac{3}{5})+2\pi n [/tex]

So for this case the possible solution is:

[tex] x= arccos(3/5) = 0.927 [/tex]

Just one solution. This is only the solution on the interval assumed.

b. 3 cos(x) + 5 = 0

We can do this:

[tex] 3 cos (x) = -5[/tex]

Then we can divide by 3 both sides and we got:

[tex] cos(x) = -\frac{5}{3}[/tex]

But we know that the cosine can't be negative so then this equation no have solutions on the reals.

c. 3 sin(x) − 1 = 0

We can do this:

[tex] 3 sin(x) = 1[/tex]

Then we can divide both sides by 3 and we got:

[tex] sin(x) = \frac{1}{3}[/tex]

The general solutions would be:

[tex] x = arcsin(\frac{1}{3}) + 2\pi n , x= \pi -arcsin (\frac{1}{3}) + 2\pi n[/tex]

[tex] x = arcsin(\frac{1}{3})=0.3398[/tex]

This is only the solution on the interval assumed.

d. tan(x) = −0.115

For this case we can solve the value of x like this:

[tex] x = arctan(-0.115) +\pi n[/tex]

And then the only possible solution for this case is:

[tex] x= -0.1145[/tex]