The Pythagorean Identity Objectives

Students know the identity `cos^2x + sin^2 x = 1`.

Students prove other trigonometric identities and simplify others by using the identity ${\displaystyle {sin}^{2}x+{cos}^{2}x=1}$. For example, students use this identity to prove that ${\displaystyle 1+{tan}^{2}x={sec}^{2}x}$ .

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