Geometry
Surface area of a cone
The curved surface plus the circular base. Not needed for volume, but they are often asked for together.
The Formula
A = pi x r x l + pi x r^2
The curved surface plus the circular base. Not needed for volume, but they are often asked for together.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| A | Surface area | square metres | Total outside area of the cone. |
| r | Radius | metres | Radius of the base. |
| l | Slant height | metres | Sloping edge length. |
What Each Symbol Means
Asquare metres
Surface area
Total outside area of the cone.
rmetres
Radius
Radius of the base.
lmetres
Slant height
Sloping edge length.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate the volume of a cone page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate The Volume Of A Cone, filed under Math. Every number the guide produces comes from substituting into this one line.