Chapter 8: Problem 80
Convert to radian measure. $$-225^{\circ}$$
Short Answer
Expert verified
-°À´Ú°ù²¹³¦µ÷5Ï€°¨µ÷4°¨
Step by step solution
01
- Understanding Degree to Radian Conversion
To convert degrees to radians, use the conversion factor: \( \frac{\text{π}}{180^{\text{°}}} \). This factor arises because \( 180^{\text{°}} \) is equal to π radians.
02
- Apply the Conversion Factor
Multiply the degree measure by \( \frac{\text{π}}{180^{\text{°}}} \): \( -225^{\text{°}} \times \frac{\text{π}}{180^{\text{°}}} \).
03
- Simplify the Fraction
Simplify the fraction formed by the multiplication: \( \frac{-225Ï€}{180} \). This can be simplified by dividing the numerator and the denominator by their greatest common divisor (GCD), which is 45.
04
- Perform the Division
Divide both the numerator and the denominator by 45: \( \frac{-225Ï€}{180} = \frac{-5Ï€}{4} \).
05
- Write the Final Answer
The radian measure for \( -225^{\text{°}} \) is \( -°À´Ú°ù²¹³¦µ÷5Ï€°¨µ÷4°¨ \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radian Measure
Radian measure is a way of expressing angles using the radius of a circle. One radian is the angle formed when the radius is wrapped around the circle's circumference. Unlike degrees, which divide a circle into 360 equal parts, radians measure angles based on the actual distance traveled along the circle's edge. Here's a simple way to think about it: if you stretch the radius length along the circle's boundary, the angle created at the center is one radian. Radians provide a more natural framework for mathematics, especially in trigonometry and calculus. In fact, one complete revolution around a circle is equal to \( 2Ï€ \) radians.
Degree Measure
Degree measure is a traditional way to describe angles by dividing a circle into 360 equal parts. Each part is one degree (\(1^{\text{°}}\)). This system is believed to have been derived from ancient Babylonians, who used a base-60 number system. When dealing with degrees, it’s simple to visualize angles: \(-90^{\text{°}}\) is a quarter circle, \(180^{\text{°}}\) is a half circle, and \(-225^{\text{°}}\) extends below the negative y-axis by half a quarter circle more. While degrees are common in navigation and daily activities, converting them into radians can simplify calculations, especially when dealing with trigonometric functions.
Pi (Ï€)
Pi (π) is a special mathematical constant and represents the ratio of a circle's circumference to its diameter. It's an irrational number, meaning it cannot be expressed as a simple fraction and its decimal form goes on forever without repeating. To approximate, we often use \(\text{π} \approx 3.14159\). Pi is fundamental in mathematics, appearing in many formulas involving circles. For angle conversions, \(π\) radians correspond to \(180^{\text{°}}\). That’s why the conversion factor \(\frac{π}{180^{\text{°}}} \) is so crucial for translating degrees to radians seamlessly.
Greatest Common Divisor (GCD)
The Greatest Common Divisor (GCD) of two numbers is the largest positive integer that divides both numbers without leaving a remainder. It’s a key concept in simplifying fractions. For instance, the fraction \(\frac{-225π}{180} \) can be simplified by determining the GCD of \(-225 \) and \(180\), which is \(45\). Dividing both the numerator and the denominator by 45 yields the simplified fraction \(\frac{-5π}{4}\). Simplification is crucial because it makes understanding and working with numbers easier, reducing complexity in both mathematical operations and their practical applications.