4. Trigonometric Functions of Any Angle
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Recall the definitions of trigonometric functions of any angle.
y/r
We are asked to fill in the blank in the following formula. sin θ = To do so, we need to recall the definitions of trigonometric functions of any angle. Let θ be an angle in standard position with (x, y) a point on the terminal side of θ and r=sqrt(x^2+y^2)≠0.
Then, we can find the values of all six trigonometric functions using the following formulas.
| Definitions of Trigonometric Functions of Any Angle | |
|---|---|
| sin θ = y/r | cos θ = x/r |
| tan θ = y/x, x ≠0 | cot θ = x/y, y ≠0 |
| sec θ = r/x, x ≠0 | csc θ = r/y, y ≠0 |
Let's take a closer look at the table and find the formula containing the expression sin θ.
| Definitions of Trigonometric Functions of Any Angle | |
|---|---|
| sin θ = y/r | cos θ = x/r |
| tan θ = y/x, x ≠0 | cot θ = x/y, y ≠0 |
| sec θ = r/x, x ≠0 | csc θ = r/y, y ≠0 |
According to the table, sin θ = yr. With this in mind, let's fill in the blank. sin θ = yr