# ACT Math 4.1 Plane Geometry

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ACT Math: Plane Geometry Drill 4, Problem 1. What is the radius of the sphere?

ACT Math | Plane Geometry |

ACT Mathematics | Plane Geometry |

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

Geometry | 3D Geometry |

Language | English Language |

Plane Geometry | Applications of geometry to three dimensions Simple 3D geometry Volume |

Product Type | ACT Math |

### Transcript

is the radius from the center of the Earth to the crispy crust.

That's R. That formula: four-thirds times quantity pi R cubed.

We just need to solve for R. So for starters...

multiply both sides by three-fourths and we have pi R cubed

equals three-fourths times 288 pi. Rewrite the equation

as pi R cubed equals 216 pi

and we can get rid of the pi on both sides by dividing it out and we're left

with R equals the cube root of 216.

So the answer is 6 and yeah, 216 is a way out their number

so you can just started by multiplying out three times three to get nine times

three with just 27. Too low. Then try four

and five and you have found your way to six pretty quick.

Anyway, the answer is R equals 6 or answer C.