ACT Math 4.1 Plane Geometry

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

ACT MathPlane Geometry
ACT MathematicsPlane Geometry
Foreign LanguageArabic Subtitled
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Geometry3D Geometry
LanguageEnglish Language
Plane GeometryApplications of geometry to three dimensions
Simple 3D geometry
Volume
Product TypeACT Math

Transcript

00:18

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

00:22

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

00:27

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

00:30

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

00:33

equals three-fourths times 288 pi. Rewrite the equation

00:38

as pi R cubed equals 216 pi

00:41

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

00:45

with R equals the cube root of 216.

00:49

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

00:55

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

01:00

three with just 27. Too low. Then try four

01:03

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

01:06

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