Math Problem Statement

The reference angle of 12π/7 radians is ____. The reference angle of 35π/8 radians is ____.

Solution

The image contains two questions asking for the reference angles of given angles in radians:

  1. The reference angle of 12π7\frac{12\pi}{7} radians.
  2. The reference angle of 35π8\frac{35\pi}{8} radians.

To solve these:

Step 1: Understanding Reference Angles

A reference angle is the smallest angle made between the terminal side of an angle and the x-axis. It's always positive and lies between 00 and π2\frac{\pi}{2} radians (or between 00^\circ and 9090^\circ).

Step 2: Convert the angles into their equivalent within [0,2π][0, 2\pi] range.

1. For 12π7\frac{12\pi}{7}:

  • 12π7\frac{12\pi}{7} radians is greater than 2π2\pi (since 2π=14π72\pi = \frac{14\pi}{7}).
  • To find the coterminal angle, subtract 2π2\pi from 12π7\frac{12\pi}{7}: 12π72π=12π714π7=2π7\frac{12\pi}{7} - 2\pi = \frac{12\pi}{7} - \frac{14\pi}{7} = -\frac{2\pi}{7}
  • Since the angle is negative, we add 2π2\pi to get it positive: 2π7+2π=12π7-\frac{2\pi}{7} + 2\pi = \frac{12\pi}{7} This angle is now positive within the first quadrant. So, the reference angle is 2π7\frac{2\pi}{7} radians.

2. For 35π8\frac{35\pi}{8}:

  • 35π8\frac{35\pi}{8} radians is greater than 2π2\pi (since 2π=16π82\pi = \frac{16\pi}{8}).
  • To find the coterminal angle, subtract 2π2\pi multiple times: 35π82π=35π816π8=19π8\frac{35\pi}{8} - 2\pi = \frac{35\pi}{8} - \frac{16\pi}{8} = \frac{19\pi}{8}
  • Since this is still greater than 2π2\pi, subtract 2π2\pi again: 19π816π8=3π8\frac{19\pi}{8} - \frac{16\pi}{8} = \frac{3\pi}{8}
  • Now 3π8\frac{3\pi}{8} lies within [0,π][0, \pi], so it is the reference angle.

Final Answers:

  1. The reference angle for 12π7\frac{12\pi}{7} is 2π7\frac{2\pi}{7} radians.
  2. The reference angle for 35π8\frac{35\pi}{8} is 3π8\frac{3\pi}{8} radians.

Would you like further explanation on how to find reference angles?

Here are 5 related questions to explore this concept further:

  1. How do reference angles differ between different quadrants?
  2. How do you calculate the reference angle for angles in degrees?
  3. What is the reference angle of 9π4\frac{9\pi}{4}?
  4. How do reference angles help in solving trigonometric functions?
  5. How do coterminal angles relate to reference angles?

Tip: When dealing with angles larger than 2π2\pi (or 360°), always reduce them by subtracting multiples of 2π2\pi.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Reference Angles
Radians

Formulas

Reference angle formula: The reference angle is the smallest positive angle between the terminal side of the angle and the x-axis.

Theorems

Reference Angle Theorem

Suitable Grade Level

Grades 10-12