IT - Defining the Ratios Lesson

Defining the Ratios

Now, recall sine, cosine and tangent from Geometry. When you learned about them, we only used acute angles, but now we want to be able to apply those concepts to any angle on the plane. So, we are going to generalize the definitions to those below:

Sine: the ratio of y to r: $\sin\theta=\frac{y}{r}$

Cosine: the ratio of x to r: $\cos\theta=\frac{x}{r}$

Tangent: the ratio of y to x: $\tan\theta=\frac{y}{x}$

Where r represents the radius of the circle r > 0: $x^2+y^2=r^2$

Watch the video below to learn about how to use the trig ratios:

The reason the Unit Circle is so important is because the radius is 1. So our new ratios become:    and 

 

 

 

 

 

 

 

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