Conversion

Reference angles are useful for creating a triangle with 90^o.


The next slide will help with a chart that will help you find any reference angle.

Reference angle

Quick Review

Dont forget that θ just means angle.

Each quadrant is split into 90^o sections.

Any reference angle < 90^o

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Understanding quadrants

Reference angle charts

The unit circle is a quick guide that helps you find values of rotational angles.


It's a master list of radian and degree measures for special right triangles

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Unit Circle

Both triangles have a special side ratio, which is why they are often used.

45, 45, 90

Just remember that the smallest side is opposite of the 30 degree angle.

30, 60, 90

Sine is the y value of the arm as it rotates.

Since it starts at a height of 0, Sine starts at the midline

Sine = y

Remember that cosine corresponds to the x value.

It's starts at 1, which is the amplitude

Cosine = x

Graphing Sine and Cosine

asin(bx) + c

a = amplitude change

b = period change

c = midline change

​acos(bx) + c