Math Problem Statement

If θ = 7π/6, then find exact values for sec(θ), csc(θ), tan(θ), and cot(θ).

Solution

Let’s solve the problem step by step.

The given angle is θ=7π6\theta = \frac{7\pi}{6}. This angle lies in the third quadrant because 7π6\frac{7\pi}{6} is slightly more than π\pi (π=6π6\pi = \frac{6\pi}{6}). The reference angle is:

Reference angle=θπ=7π6π=π6.\text{Reference angle} = \theta - \pi = \frac{7\pi}{6} - \pi = \frac{\pi}{6}.

The trigonometric functions in the third quadrant are as follows:

  • Sine and cosecant (sinθ,cscθ\sin \theta, \csc \theta) are negative.
  • Cosine and secant (cosθ,secθ\cos \theta, \sec \theta) are negative.
  • Tangent and cotangent (tanθ,cotθ\tan \theta, \cot \theta) are positive.

The exact values for sin\sin, cos\cos, and tan\tan of π6\frac{\pi}{6} (from reference angles) are: sin(π6)=12,cos(π6)=32,tan(π6)=13.\sin\left(\frac{\pi}{6}\right) = \frac{1}{2}, \quad \cos\left(\frac{\pi}{6}\right) = \frac{\sqrt{3}}{2}, \quad \tan\left(\frac{\pi}{6}\right) = \frac{1}{\sqrt{3}}.

Using these values:

  1. sec(θ)\sec(\theta): sec(θ)=1cos(θ)=132=23=233.\sec(\theta) = \frac{1}{\cos(\theta)} = \frac{1}{-\frac{\sqrt{3}}{2}} = -\frac{2}{\sqrt{3}} = -\frac{2\sqrt{3}}{3}.

  2. csc(θ)\csc(\theta): csc(θ)=1sin(θ)=112=2.\csc(\theta) = \frac{1}{\sin(\theta)} = \frac{1}{-\frac{1}{2}} = -2.

  3. tan(θ)\tan(\theta): tan(θ)=sin(θ)cos(θ)=1232=13=33.\tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)} = \frac{-\frac{1}{2}}{-\frac{\sqrt{3}}{2}} = \frac{1}{\sqrt{3}} = \frac{\sqrt{3}}{3}.

  4. cot(θ)\cot(\theta): cot(θ)=1tan(θ)=133=3.\cot(\theta) = \frac{1}{\tan(\theta)} = \frac{1}{\frac{\sqrt{3}}{3}} = \sqrt{3}.

Final answers:

sec(θ)=233,csc(θ)=2,tan(θ)=33,cot(θ)=3.\sec(\theta) = -\frac{2\sqrt{3}}{3}, \quad \csc(\theta) = -2, \quad \tan(\theta) = \frac{\sqrt{3}}{3}, \quad \cot(\theta) = \sqrt{3}.

Let me know if you'd like more details or have questions.

Related Questions:

  1. What is the reference angle for θ=5π4\theta = \frac{5\pi}{4}?
  2. How do you determine the quadrant of a given angle?
  3. What are the signs of trigonometric functions in all quadrants?
  4. How is the secant function related to cosine?
  5. Why does the tangent of π6\frac{\pi}{6} simplify to 33\frac{\sqrt{3}}{3}?

Tip: Always start by finding the reference angle and determining the quadrant when solving trigonometric problems!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Quadrants
Reference Angles

Formulas

sec(θ) = 1 / cos(θ)
csc(θ) = 1 / sin(θ)
tan(θ) = sin(θ) / cos(θ)
cot(θ) = 1 / tan(θ)

Theorems

Trigonometric Ratios in Standard Position

Suitable Grade Level

Grades 10-12