Triangular Prisms
Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 35 of 62.
A right triangular prism's net is two triangles and three rectangles. The triangles are the ends. Each rectangle is one side of the triangle stretched along the prism's length.
Here the ends are right triangles with legs 4 and 3, so the two ends together make 2 × 1/2 × 4 × 3 = 12. The rectangles are 4, 3 and 5 wide and all 6 long, so they make (4 + 3 + 5) × 6 = 72. The surface area is 12 + 72 = 84.
The rule is Surface area of a prism: the two ends plus the perimeter of an end times the length. This time every side of the triangle counts, the longest one too, because each one is a face.
Challenge
The prism's ends are right triangles. 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: Pyramids7Surface Area of Prisms
Nets and Surface AreaVolume or Surface Area?A Missing Edge AgainTriangular PrismsThe Hidden Side FirstRecap: Prism Surfaces2Volume 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