# ACT Math 1.4 Trigonometry

###### Recommendation

### Want a study guide too?

ACT Math: Trigonometry Drill 1, Problem 4. Can you find the sine?

ACT Math | Trigonometry |

ACT Mathematics | Trigonometry |

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

Functions | Extend the domain of trigonometric functions using the unit circle |

Geometry | Right Triangles and Trigonometry |

Language | English Language |

Product Type | ACT Math |

Trigonometry | SOHCAHTOA (values and properties of trig functions) Solving trigonometric equations Trig identities |

### Transcript

Just think of pi as a 180 degrees. How did we come up with that?

Well the formula for the circumference of a circle is 2

pi times the radius of the circle.

Well in a unit circle, that's where the radius is just 1,

we can describe a full 360 degrees of a circle as 2pi

times one or just 2pi radians

if 360 degrees is 2pi radians...half of 360 is 180 or

pi radians. Plug in 180 for pi

in sine over pi over 4... 180 divided by four is 45

Sine of 45 degrees is the square root of 2 over 2.

Option D is our answer.