Slant Height First
Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 44 of 62.
If a pyramid is given by its base edge and its true height, the surface area still needs the slant height. Find it from the right triangle inside, then use the surface rule.
This is the pyramid from the last lesson, given by its height 4 instead. Half the base is 3, so s^2 = 4^2 + 3^2 = 25 and s = 5. Then the surface area is 6^2 + 2 × 6 × 5 = 96, as before.
On the board: tap the slant height and pick Slant height, then tap the pyramid and pick Surface area of a pyramid.
Challenge
The pyramid's base edge and height are labelled. Find its surface area, then press Check.
Try it yourself
Find the marked part of the figure
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Surface Area & Volume
1Solids and Their Parts
Faces, Edges and VerticesPrisms and CylindersPyramids and ConesHeight or Slant Height?Spheres and HemispheresRecap: Parts of Solids4Pyramids
Volume of a PyramidThe Slant HeightHeight From the SlantHeight From the VolumeRecap: Pyramids2Volume of Prisms
Volume of a CuboidVolume of a PrismAny Triangle EndA Missing EdgeRecap: Prism Volume3Cylinders
Volume of a CylinderHeight From the VolumeRadius From the VolumeEnough to Find It?Recap: Cylinders6Spheres and Hemispheres
Volume of a SphereHalf a SphereRadius From the VolumeSphere in a CylinderRecap: Spheres9Pyramids and Cones Outside
Surface of a PyramidSlant Height FirstSurface of a ConeThe Cone: Slant FirstRecap: Pyramid Surfaces