PC.T.1.4: Use special triangles to determine geometrically the values of sine, cosine, tangent for , and use the unit circle to express the values of sine, cosine, and tangent for 𝜋 − 𝑥, 𝜋 + 𝑥, and 2𝜋 − 𝑥 in terms of their values for x, where x is any real number.

Use special triangles to determine geometrically the values of sine, cosine, tangent for , and use the unit circle to express the values of sine, cosine, and tangent for 𝜋 − 𝑥, 𝜋 + 𝑥, and 2𝜋 − 𝑥 in terms of their values for x, where x is any real number.

Example Problems

Find the exact value:

\cos(90°)

Find the exact value:

\sin{60°}

Find the exact value:

\cos(\pi)

Khan Academy Resources

Trig values of special angles Trig identities from reflections and rotations Intersection points of y=sin(x) and y=cos(x)Sine & cosine identities: periodicity Cosine equation algebraic solution set Trig values of π/4

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