Just like in our last video, this lesson is going to show you some incredibly powerful identities.
The Double Angle Identities!
We will begin by looking at all the double angle identities for:
- Sine
- Cosine
- Tangent
and show how we can use them to simplify expressions.
This skill will prove particularly useful in calculus, as SOS Math accurately states, when we are trying to integrate complicated trig functions, so we’re going to ensure that you know these awesome identities well so you’ll always know them and be able to use them effectively.
Similar to the Sum and Difference Identities, we will see how Double Angle Identities can help us to evaluate trigonometric functions that are not on the Unit Circle.
Indeed, some examples will be sneaky, which will only help to show off your amazing trig powers to your friends!
Cosine Double Angle Identity
What’s so cool about these identities, is that throughout our journey of proving fundamental identities, we can begin to see how one function can be easily expressed as a sum or difference or multiple of another.
They’re all related!
In fact, with the power of Identities, we can now evaluate problems dealing with complicated Reference Angles and Triangles.
Double Angle Identities – Video
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