Math Problem Statement

Solve the trigonometric equation for all values 0 ≤ x < 2π: √3 cot x = -3.

Solution

To solve the given trigonometric equation:

3cotx=3\sqrt{3} \cot x = -3

for 0x<2π0 \leq x < 2\pi, let us proceed step by step.


Step 1: Isolate cotx\cot x

Divide both sides of the equation by 3\sqrt{3}: cotx=33=3.\cot x = -\frac{3}{\sqrt{3}} = -\sqrt{3}.


Step 2: Recall the definition of cotx\cot x

cotx=cosxsinx.\cot x = \frac{\cos x}{\sin x}. The equation implies that: cosxsinx=3.\frac{\cos x}{\sin x} = -\sqrt{3}.


Step 3: Determine the reference angle

The reference angle is determined by considering the absolute value of cotx=3\cot x = \sqrt{3}. From standard trigonometric values: cotπ6=3.\cot \frac{\pi}{6} = \sqrt{3}. Thus, the reference angle is: α=π6.\alpha = \frac{\pi}{6}.


Step 4: Find the quadrants where cotx<0\cot x < 0

The cotangent function is negative in the second and fourth quadrants. Thus, the solutions are: x=πα(second quadrant)x = \pi - \alpha \quad \text{(second quadrant)} x=2πα(fourth quadrant).x = 2\pi - \alpha \quad \text{(fourth quadrant)}.


Step 5: Substitute the reference angle

x=ππ6=5π6,x = \pi - \frac{\pi}{6} = \frac{5\pi}{6}, x=2ππ6=11π6.x = 2\pi - \frac{\pi}{6} = \frac{11\pi}{6}.


Final Answer:

The solutions are: x=5π6,11π6.x = \frac{5\pi}{6}, \frac{11\pi}{6}.

Would you like further explanation or visualizations for any step?


Related Questions:

  1. What is the general solution for cotx=3\cot x = -\sqrt{3}?
  2. How do you determine the reference angle for other trigonometric ratios?
  3. What is the domain of the cotangent function?
  4. Why is cotangent negative in the second and fourth quadrants?
  5. Can this method be extended to solve similar equations, such as cotx=2\cot x = -2?

Tip:

Always verify which quadrants satisfy the sign of the trigonometric function when solving equations!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Cotangent Function
Unit Circle
Reference Angles

Formulas

cot x = cos x / sin x
Reference angle determination: cot π/6 = √3

Theorems

Properties of Trigonometric Functions
Signs of Trigonometric Functions in Quadrants

Suitable Grade Level

Grades 10-12