Trig Quadrant Question: Solving for secx=-5.2, 0≤x≤2π

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In summary, for the equation \sec x = -5.2, with the given restrictions, there are two solutions: x = 1.76 and x = 4.52. For the evaluation of \cot 4.47, the correct answer is 0.25, not 0.23. And for the equation \sec x = -5.2, there are two solutions, as cos is positive in both quadrant 3 and 4.
  • #1
Destrio
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Solve: secx=-5.2, 0≤x≤2π

I'm getting 2 answers:
1.76, 4.52

The answer key is telling me there is only one
1.76

How do I only get 1 answer from this?

Thanks,
 
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  • #2
Evaluate: cot4.47

I'm getting .23 when i plug in: tan(1/4.47)

but the answer key says .25
am I doing something wrong?

thanks
 
  • #3
1. [tex] \sec x = -5.2, \; 0\leq x\leq 2\pi [/tex]

[tex] \frac{1}{\cos x} = - 5.2 [/tex]

[tex] \cos x = -\frac{1}{5.2} = [/tex]

[tex] \arccos(\cos x) = 1.76 [/tex]

[tex] x = 1.76 [/tex]2. [tex] \cot 4.47 = \frac{1}{\tan 4.47}[/tex] not [tex] \tan(\frac{1}{4.47}) [/tex]
 
  • #4
thanks, I see what I did wrong for #2

but, why doesn't #1 have 2 answers?
 
  • #5
Because the second answer is in quadrant 4, where cos is positive.
 
  • #6
No, it's in the 3rd quadrant. There should be 2 solutions.
 
  • #7
Yes, there should be 2 answers. Cheers. :)
 
  • #8
Alright
Thanks everyone
 

1. What are the four quadrants in trigonometry?

The four quadrants in trigonometry are labeled as Quadrant I, II, III, and IV. They are formed by the x-axis and y-axis, which intersect at the origin (0,0).

2. How do we determine which quadrant a trigonometric angle belongs to?

The quadrant of a trigonometric angle can be determined by looking at the signs (+/-) of the x and y coordinates of the point where the angle intersects the unit circle. If both coordinates are positive, the angle is in Quadrant I. If x is negative and y is positive, the angle is in Quadrant II. If both coordinates are negative, the angle is in Quadrant III. And if x is positive and y is negative, the angle is in Quadrant IV.

3. What is the relationship between trigonometric functions and quadrants?

The relationship between trigonometric functions and quadrants is that the sign of the trigonometric functions (sine, cosine, tangent) depends on the quadrant in which the angle lies. For example, in Quadrant I, all trigonometric functions are positive, in Quadrant II, only sine is positive, in Quadrant III, only tangent is positive, and in Quadrant IV, only cosine is positive.

4. How do we solve trigonometric equations in different quadrants?

To solve trigonometric equations in different quadrants, we need to consider the restrictions of each quadrant. For example, in Quadrant I, all trigonometric functions are positive, so we can use the basic trigonometric ratios to solve equations. In Quadrant II, the sine function is positive, so we can use the reciprocal function cosecant to solve equations. In Quadrant III, the tangent function is positive, so we can use the reciprocal function cotangent to solve equations. And in Quadrant IV, the cosine function is positive, so we can use the reciprocal function secant to solve equations.

5. What is the importance of understanding trigonometric quadrants?

Understanding trigonometric quadrants is important because it helps us to accurately determine the signs of trigonometric functions and solve trigonometric equations. It also allows us to better visualize and understand the graphs of trigonometric functions, as each quadrant has a unique pattern of positive and negative values. Moreover, it is essential in real-world applications, such as navigation, to determine the direction and location of objects.

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