# ACT Math 4.1 Trigonometry

ACT Math: Trigonometry Drill 4, Problem 1. Simplify the expression.

ACT Math | Trigonometry |

ACT Mathematics | Trigonometry |

Foreign Language | Arabic Subtitled Chinese Subtitled Korean Subtitled Spanish Subtitled |

Geometry | Right Triangles and Trigonometry |

Language | English Language |

Product Type | ACT Math |

Trigonometry | Solving trigonometric equations Trig identities |

### Transcript

the fourth alpha as sine squared alpha squared

minus cosine squared alpha squared... because they're the same thing.

Now we need to call on our good friend - the

difference of two squares formula: x squared minus y squared equals x minus y times x plus y.

If we pretend that sin squared alpha is x

and cos squared alpha is y, we can simplify it to:

sin squared alpha minus cosine squared alpha times sin squared alpha PLUS cosine squared

alpha. We also know that (sin2⍺

+ cos2⍺) = 1 from the fundamental trig identities.

Now all we're left with is (sin2⍺ -- cos2⍺)...

...which happens to be answer D.