Skip to main content
Ch. 1 - Angles and the Trigonometric Functions
1์žฅ, ๋ฌธ์ œ 99

Find two values of ฮธ, 0 โ‰ค ฮธ < 2๐œ‹, that satisfy each equation.
sin ฮธ = โˆš2/2

๊ฒ€์ฆ๋œ ๋‹จ๊ณ„๋ณ„ ์•ˆ๋‚ด
1
Recall the range of the sine function: \(\sin \theta\) can only take values between \(-1\) and \(1\). Since \(\frac{\sqrt{2}}{2}\) is approximately \(0.707\), it is within this range, so solutions exist.
Recognize that \(\sin \theta = \frac{\sqrt{2}}{2}\) corresponds to a well-known angle in the unit circle. Identify the reference angle \(\alpha\) such that \(\sin \alpha = \frac{\sqrt{2}}{2}\).
From the unit circle, the reference angle \(\alpha\) is \(\frac{\pi}{4}\) because \(\sin \frac{\pi}{4} = \frac{\sqrt{2}}{2}\).
Since sine is positive in the first and second quadrants, find the two angles \(\theta\) in \([0, 2\pi)\) where \(\sin \theta = \frac{\sqrt{2}}{2}\). These are \(\theta = \alpha\) and \(\theta = \pi - \alpha\).
Write the two solutions explicitly as \(\theta = \frac{\pi}{4}\) and \(\theta = \pi - \frac{\pi}{4}\), which simplifies to \(\theta = \frac{3\pi}{4}\).

๋น„์Šทํ•œ ๋ฌธ์ œ์— ๋Œ€ํ•œ ๊ฒ€์ฆ๋œ ์˜์ƒ ๋‹ต๋ณ€:

์ด ์˜์ƒ ํ•ด๋ฒ•์€ ์œ„ ๋ฌธ์ œ์— ๋„์›€์ด ๋œ๋‹ค๊ณ  ํŠœํ„ฐ๋“ค์ด ์ถ”์ฒœํ•œ ๊ฒƒ์ž…๋‹ˆ๋‹ค.
์˜์ƒ ๊ธธ์ด:
2m
๋„์›€์ด ๋˜์—ˆ๋‚˜์š”?

์ฃผ์š” ๊ฐœ๋…

์งˆ๋ฌธ์— ์˜ฌ๋ฐ”๋ฅด๊ฒŒ ๋‹ตํ•˜๊ธฐ ์œ„ํ•ด ๋ฐ˜๋“œ์‹œ ์ดํ•ดํ•ด์•ผ ํ•˜๋Š” ํ•ต์‹ฌ ๊ฐœ๋…๋“ค์€ ๋‹ค์Œ๊ณผ ๊ฐ™์Šต๋‹ˆ๋‹ค.

Unit Circle and Angle Measurement

The unit circle is a circle with radius 1 centered at the origin, used to define trigonometric functions for all angles. Angles are measured in radians from 0 to 2ฯ€ for one full rotation, which helps identify the sine values corresponding to specific angles.
์ถ”์ฒœ ์˜์ƒ:
06:11
Introduction to the Unit Circle

Sine Function Values and Their Range

The sine function outputs values between -1 and 1. Knowing that sin ฮธ = โˆš2/2 corresponds to specific standard angles (ฯ€/4 and 3ฯ€/4) within the interval 0 โ‰ค ฮธ < 2ฯ€ is essential for finding solutions.
์ถ”์ฒœ ์˜์ƒ:
4:22
Domain and Range of Function Transformations

Finding Multiple Solutions in One Period

Since sine is positive in the first and second quadrants, there are two angles between 0 and 2ฯ€ where sin ฮธ equals โˆš2/2. Understanding the symmetry of sine values in these quadrants allows identification of both solutions.
์ถ”์ฒœ ์˜์ƒ:
5:37
Introduction to Cotangent Graph