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正弦函数与余弦函数
正弦函数与余弦函数是什么？它们如何由一个点沿单位圆运动而产生？
1. Introduction
Introduction
2. The definition of the sine function
The definition of the sine function
3. The definition of the cosine function
The definition of the cosine function
4. Properties of the sine and cosine functions
Properties of the sine and cosine functions
5. Sine values from the unit circle
On the unit circle, what are sin(pi/4) and sin(pi/3)?
6. Cosine values at special angles
Which set of exact cosine values at pi/6, 5pi/6 and -pi/3 is correct?
7. Cosine after subtracting periods
Using periodicity, what is cos(11pi/4)? Give the exact value as a signed square root over 2, e.g. "-sqrt(2)/2".
8. Choosing the right root
A unit-circle point lies in Quadrant II and has sin(t) = 1/2. What is cos(t)?
9. Quadrants where cosine is negative
In which quadrants is cos(t) negative, and where do the sine and cosine graphs change most rapidly?
10. Largest intervals from the graphs
Which statement correctly describes the sine and cosine graphs' decreasing or increasing stretches?
11. Cosine is negative in Quadrant II
In Quadrant II, the cosine of an angle is negative.