Math Problem Statement

solve

Given that 2sin^2(x) - 3sin(x) = 2, find the exact values of sin(x). Hence solve the equation 2sin^2(x) - 3sin(x) = 2 for 0° < x < 360°.

Solution

Let's solve the given problem step-by-step.

(a) Given the equation:

2sin2x3sinx=22 \sin^2 x - 3 \sin x = 2

We are to find the exact values of sinx\sin x.

  1. Let y=sinxy = \sin x, then the equation becomes: 2y23y=22y^2 - 3y = 2

  2. Rearrange it to form a standard quadratic equation: 2y23y2=02y^2 - 3y - 2 = 0

  3. Use the quadratic formula to solve for yy: y=b±b24ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

    Here, a=2a = 2, b=3b = -3, and c=2c = -2.

  4. Substituting these values: y=3±(3)242(2)22y = \frac{3 \pm \sqrt{(-3)^2 - 4 \cdot 2 \cdot (-2)}}{2 \cdot 2} y=3±9+164y = \frac{3 \pm \sqrt{9 + 16}}{4} y=3±254y = \frac{3 \pm \sqrt{25}}{4} y=3±54y = \frac{3 \pm 5}{4}

  5. This gives two solutions: y=84=2ory=24=0.5y = \frac{8}{4} = 2 \quad \text{or} \quad y = \frac{-2}{4} = -0.5

Since sinx\sin x must be between -1 and 1, the valid solution is: sinx=0.5\sin x = -0.5

(b) Solve the equation 2sin2x3sinx=22 \sin^2 x - 3 \sin x = 2 for 0<x<3600^\circ < x < 360^\circ:

From part (a), we found: sinx=0.5\sin x = -0.5

The solutions for sinx=0.5\sin x = -0.5 in the interval 0<x<3600^\circ < x < 360^\circ are: x=210orx=330x = 210^\circ \quad \text{or} \quad x = 330^\circ

Final Answer:

  • (a) The exact value of sinx\sin x is 0.5-0.5.
  • (b) The solutions for xx in the interval 0<x<3600^\circ < x < 360^\circ are: x=210orx=330x = 210^\circ \quad \text{or} \quad x = 330^\circ

Would you like a detailed breakdown of any specific step?

Related Questions:

  1. How do you derive the quadratic formula from a standard quadratic equation?
  2. What are the typical steps to solve a trigonometric equation?
  3. How do you determine the angles that satisfy a trigonometric equation within a specific interval?
  4. Why is it necessary to check if solutions lie within the valid range for trigonometric functions?
  5. How can you solve similar trigonometric equations involving cosine or tangent?

Tip: Always verify that solutions fall within the specified interval and range for trigonometric functions. This ensures accurate answers!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Quadratic Equations

Formulas

Quadratic formula: y = (-b ± √(b² - 4ac)) / 2a

Theorems

Solutions of trigonometric equations within a specific interval

Suitable Grade Level

Grades 10-12