Math Problem Statement

Sketch each angle in standard position. State which quadrant the angle terminates in and the measure of the reference angle. Additionally, solve trigonometric problems involving points on the terminal arm of angles and compute reference angles for given points.

Solution

Let's break down the questions and solve them step by step:


Problem 3:

For each angle, identify the quadrant it terminates in and the reference angle.

a) 200°

  • Quadrant: 200° lies between 180° and 270°, so it is in Quadrant III.
  • Reference Angle: The reference angle is 200°180°=20°200° - 180° = 20°.

b) 130°

  • Quadrant: 130° lies between 90° and 180°, so it is in Quadrant II.
  • Reference Angle: The reference angle is 180°130°=50°180° - 130° = 50°.

c) 90°

  • Quadrant: 90° lies directly on the positive yy-axis. It is not in a specific quadrant.
  • Reference Angle: Since it lies on the axis, the reference angle is .

d) 330°

  • Quadrant: 330° lies between 270° and 360°, so it is in Quadrant IV.
  • Reference Angle: The reference angle is 360°330°=30°360° - 330° = 30°.

Problem 4:

The terminal arm passes through the point (3,6)(-3, 6).

a) Draw this angle in standard position:

  • The terminal arm passes through (3,6)(-3, 6), so it is in Quadrant II.

b) Determine the exact distance from the origin to the point Q:

  • The distance is calculated using the distance formula: r=x2+y2=(3)2+62=9+36=45=35.r = \sqrt{x^2 + y^2} = \sqrt{(-3)^2 + 6^2} = \sqrt{9 + 36} = \sqrt{45} = 3\sqrt{5}.

c) Determine the exact values for sinθ\sin \theta, cosθ\cos \theta, and tanθ\tan \theta:

  • Using r=35r = 3\sqrt{5}:
    • sinθ=yr=635=25=255\sin \theta = \frac{y}{r} = \frac{6}{3\sqrt{5}} = \frac{2}{\sqrt{5}} = \frac{2\sqrt{5}}{5},
    • cosθ=xr=335=15=55\cos \theta = \frac{x}{r} = \frac{-3}{3\sqrt{5}} = \frac{-1}{\sqrt{5}} = \frac{-\sqrt{5}}{5},
    • tanθ=yx=63=2\tan \theta = \frac{y}{x} = \frac{6}{-3} = -2.

d) Determine the value of θ\theta:

  • The angle is in Quadrant II, and the reference angle θref\theta_{\text{ref}} is calculated as: θref=arctanyx=arctan63=arctan(2).\theta_{\text{ref}} = \arctan\left|\frac{y}{x}\right| = \arctan\left|\frac{6}{-3}\right| = \arctan(2). So, θ=180°θref\theta = 180° - \theta_{\text{ref}}.

Problem 5:

Find points corresponding to the reference angle of P(2,5)P(2, -5).

  • The reference angle is the angle formed in Quadrant IV where tanθ=52\tan \theta = \frac{-5}{2}.
  • Symmetrical points:
    • Quadrant I: (2,5)(2, 5),
    • Quadrant II: (2,5)(-2, 5),
    • Quadrant III: (2,5)(-2, -5).

Would you like a detailed sketch for these solutions or further explanation on any part?


Follow-up Questions:

  1. How is the reference angle related to the terminal angle?
  2. Can you explain why trigonometric ratios change signs in different quadrants?
  3. What is the geometric meaning of a reference angle?
  4. How would you compute θ\theta if given only a tangent ratio and its quadrant?
  5. Why does the distance formula use squares of coordinates?

Tip:

Always associate the reference angle with the closest axis—it simplifies solving trigonometric problems.

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Math Problem Analysis

Mathematical Concepts

Reference angles
Trigonometric ratios (sin, cos, tan)
Quadrants in a coordinate system
Standard position of angles

Formulas

Reference angle = |angle - closest axis angle|
Distance formula: r = sqrt(x^2 + y^2)
Trigonometric ratios: sin(θ) = y/r, cos(θ) = x/r, tan(θ) = y/x

Theorems

Pythagorean theorem
Symmetry of angles in quadrants

Suitable Grade Level

Grades 9-12