What is the value of the angle marked with xxx?

For 0 ≤ ϴ < 2π, how many solutions are there to tan(StartFraction theta Over 2 EndFraction) = sin(ϴ)? Note: Do not include va

Black_prince [1.1K]

Answer:

3 solutions:

$\theta={0, \frac{\pi}{2}, \frac{3\pi}{2}}$

Step-by-step explanation:

So, first of all, we need to figure the angles that cannot be included in our answers out. The only function in the equation that isn't defined for some angles is $tan(\frac{\theta}{2})$ so let's focus on that part of the equation first.

We know that:

$tan(\frac{\theta}{2})=\frac{sin(\frac{\theta}{2})}{cos(\frac{\theta}{2})}$

therefore:

$cos(\frac{\theta}{2})\neq0$

so we need to find the angles that will make the cos function equal to zero. So we get:

$cos(\frac{\theta}{2})=0$

$\frac{\theta}{2}=cos^{-1}(0)$

$\frac{\theta}{2}=\frac{\pi}{2}+\pi n$

or

$\theta=\pi+2\pi n$

we can now start plugging values in for n:

$\theta=\pi+2\pi (0)=\pi$

if we plugged any value greater than 0, we would end up with an angle that is greater than $2\pi$ so, that's the only angle we cannot include in our answer set, so:

$\theta\neq \pi$

having said this, we can now start solving the equation:

$tan(\frac{\theta}{2})=sin(\theta)$

we can start solving this equation by using the half angle formula, such a formula tells us the following:

$tan(\frac{\theta}{2})=\frac{1-cos(\theta)}{sin(\theta)}$

so we can substitute it into our equation:

$\frac{1-cos(\theta)}{sin(\theta)}=sin(\theta)$

we can now multiply both sides of the equation by $sin(\theta)$

so we get:

$1-cos(\theta)=sin^{2}(\theta)$

we can use the pythagorean identity to rewrite $sin^{2}(\theta)$ in terms of cos:

$sin^{2}(\theta)=1-cos^{2}(\theta)$

so we get:

$1-cos(\theta)=1-cos^{2}(\theta)$

we can subtract a 1 from both sides of the equation so we end up with:

$-cos(\theta)=-cos^{2}(\theta)$

and we can now add $cos^{2}(\theta)$

to both sides of the equation so we get:

$cos^{2}(\theta)-cos(\theta)=0$

and we can solve this equation by factoring. We can factor $cos(\theta)$ to get:

$cos(\theta)(cos(\theta)-1)=0$

and we can use the zero product property to solve this, so we get two equations:

Equation 1:

$cos(\theta)=0$

$\theta=cos^{-1}(0)$

$\theta={\frac{\pi}{2}, \frac{3\pi}{2}}$

Equation 2:

$cos(\theta)-1=0$

we add a 1 to both sides of the equation so we get:

$cos(\theta)=1$

$\theta=cos^{-1}(1)$

$\theta=0$

so we end up with three answers to this equation:

$\theta={0, \frac{\pi}{2}, \frac{3\pi}{2}}$

7 0

3 years ago

Which of the following represents a valid first step to solving this system of equations using the substitution method?

Phoenix [80]

Answer:

2(2y - 1) - y = 7

Step-by-step explanation:

I guess the 2 equations are

2x - y = 7

x = 2y - 1

substitution message that you use one equation to express one variable by the other, and then you use that in the other equation to get one equation for one variable. then you solve for that, and use that result in the first equation to since for the second variable.

the equations are already defined that way, that the second equation directly defines x as an excision of y.

so, this needs to be used then in the first equation.

and that makes

2(2y - 1) - y = 7

the correct first step.

7 0

2 years ago

Sam is flying a kite. The length of the kite string is 80 meters, and it makes an angle of 75 with the ground. The height of the

GuDViN [60]

You don't say if the answer needs to be rounded
the height is 77.27 meters ( not rounded)

see attached picture for solution:

6 0

3 years ago

Read 2 more answers

True or false 49 is a irratinal number

Vikki [24]

Answer:

false

Step-by-step explanation:

49 is a rational no

brainliest pleazzzz......

7 0

3 years ago

Read 2 more answers

Can you relly much help me do this

slava [35]

Hey!
So It would be set up as .75n -2 = 10
.75 is the same as 3/4
Now add 2 to both sides
.75n = 12
now we want to get n alone so that we know what the number is, so divide .75 to both sides since it's multiplied to n
n=16
The answer is D!
Hope this helps!

5 0

3 years ago