ACT Preparation / Unit 14 ACT 1313 short lesson, about 20 seconds
Spheres and Cones
Captions available
The idea
A sphere's volume is (4/3)πr³ and its surface area 4πr². A cone's volume is (1/3)πr²h, one third of the cylinder with the same base and height.
In practice
A sphere of radius 3 has volume 36π; a cone of radius 3 and height 10 has volume 30π.
Where people slip
Cube the radius for volume; square it for surface area.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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