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Glossary

Look up any term from this course. Each entry links back to the lesson that taught it.

Glossary of course terms
Term	Definition	Lesson
Composite solid	$A solid made by joining simpler solids together; volumes always add, but surface area excludes hidden, joined faces.$	Composite Solids
Cube	$A cuboid with all three dimensions equal to s. Volume = s^{3}, surface area = 6 s^{2} .$	Volume and Surface Area of a Cube
Density	$Mass \div volume — how tightly packed a material's mass is within its volume.$	Density and Real-World Applications
Face, edge, vertex	$A face is a surface, an edge is where two faces meet, and a vertex is a corner point.$	Naming 3D Solids
Hemisphere	$Exactly half of a sphere. Volume and curved surface area are half the full sphere's formulas.$	Review and Practice
Net	$A 2 D shape made of a solid's faces laid out flat, which folds up into the 3 D solid.$	Nets of Solids
Scaling solids	$If linear dimensions scale by k, surface area scales by k^{2} and volume scales by k^{3} .$	Scaling Solids
Slant height	$The distance from a cone's base edge to its apex along the surface: l = \sqrt(r^{2} + h^{2}).$	Surface Area of a Cone
Surface area of a cone	$π r^{2} + πrl, using the slant height l.$	Surface Area of a Cone
Surface area of a cuboid	$2 (lw + lh + wh), for a cuboid with length l, width w, and height h.$	Surface Area of a Cuboid
Surface area of a cylinder	$2 π r^{2} + 2 πrh, for a cylinder with radius r and height h.$	Surface Area of a Cylinder
Surface area of a sphere	$4 π r^{2} — exactly four times the area of a circle with the same radius.$	Surface Area of a Sphere
Volume of a cone	$\frac{1}{3} π r^{2} h — exactly one third of a cylinder with the same base and height.$	Volume of a Cone
Volume of a cuboid	$length \times width \times height.$	Volume of a Cuboid
Volume of a cylinder	$πr²h, for a cylinder with radius r and height h.$	Volume of a Cylinder
Volume of a sphere	$\frac{4}{3} π r^{3}, for a sphere with radius r .$	Volume of a Sphere