# Sin and Cos of Complementary Angles

Videos and lessons to help High School students learn how to explain and use the relationship between the sine and cosine of complementary angles.

sin θ = cos(90 - θ)
Common Core: HSG-SRT.C.7

Sine and Cosine Relationships of Complementary angles. Cofunctions
Sine and Cosine of complementary angles are congruent.

Complementary Angle Theorem.

Complementary Angles with Trig Ratios
Complementary angles in trigonometry.

Complementary angles in trig.

Cofunctions of Complementary Angles.

Cofunction Identities
This video explains the cofunction identities and how to determine cofunctions given a function value. Most cofunction values are verified on a calculator.

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