Question

Write the x value in the unit circle in terms of theta the measure of the central angle

Answer 1

x = cos(θ)

Explanation:

The above relation is one that is usefully committed to memory. The mnemonic SOH CAH TOA can help you remember it, along with ...

y = sin(θ)

The x-value is adjacent to the central angle; the y-value is opposite. The hypotenuse of the relevant triangle in a unit circle is 1.

The x-value is ...

x = cos(θ)

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These relationships are necessary to convert from rectangular to polar coordinates and vice versa. They are also helpful when working vector problems.