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# How to remember the Unit Circle

### Use this Math trick as an easy way to remember the unit circle

Your hand can be used as a reference to help remember the unit circle

The tips of your fingers remind you that will be taking the square root of the numerator, and your palm reminds you that the denominator will equal two.

See Figure 1. for what each part of hand will represent.

Your pinkie represents 0 degrees, your ring finger equals 30 degrees, the middle finger equals 45, and your pointing finger equals 60 degrees on the Unit Circle.

Cosine is written first, followed by Sine

## How do you remember the sign values for the four quadrants of the unit circle?

One easy method is to think of each Quadrant in terms of the x and y axis.
If you are graphing on a coordinate plane you know all values to the right of the y axis are positive, and values to the left are negative.
In the same way everything above the x axis has a positive value, and items below the x axis have a negative value.

Look at Quadrant 1, all items in this quadrant are right of the y axis, and above the x axis.  Therefore, the sign values for this Quadrant are (+, +).

Remember the x value is always written before the y value.

Look at Quadrant 2, all sign values in this Quadrant are left of the y axis, and above the x axis.
Therefore the values for x are negative, and positive for y values so you write the values (-,+).

Quadrant 3 has sign values (-,-) and Quadrant 4 has sign values (+,-).

The unit circle has a radius of one. The position (1, 0) is where x has a value of 1, and y has a value of 0. This starting position in the unit circle represents 0 degrees.

The position (0,1) represents 90 degrees.

The position (-1,0) represents 180 degrees.

The position (0, -1) represents 270 degrees.

A full circle is 360 degrees and ends at the starting position (0, 1)

You can remember the trig function values by remembering

All  Students  Take  Calculus

A = All positive
S= Sine and it’s reciprocal cosecant  are positive
T = Tangent and it’s reciprocal cotangent are positive
C = Cosine and it’s reciprocal secant are positive