2Instructions for useThere are 9 worked examples shown in this PowerPointA red dot will appear top right of screen to proceed to the next slide.Click the navigation bar to the left of screen to access relevant slides.
33 easy steps to calculate the Surface Area of a solid figure Determine the number of surfaces and the shape of the surfaces of the solidApply the relevant formula for the area of each surfaceSum the areas of each surface
4Surface Area – Basic concept 4 rectangular faces and2 square facesrectanglerectanglerectanglesquaresquarerectangleDetermine the number and shape of the surfaces that make up the solid.When you’ve done all that find the area of each face and then find the total of the areas.It might be easier to think of the net of the solid.
5Four rectangular faces Square prismFind the surface area of this figure with square base 5 cm and height 18 cmTwo square facesFour rectangular faces18 cm5 cm
6Rectangular prism Now sum these areas Find the surface area of this figure with length 10 cm, width 15 cm and height 12 cm.Now sum these areas20 cm15 cm5 cm
7Triangular Prism 1 2 3 Recall Find the surface area of this figure with dimensions as marked.12 cm10 cm68Use Pythagoras’ theorem to find the height of the triangle!12 cm20 cm10 cmHence, total surface areaDetermine the number of faces and the shape of each faceRecall1Apply the area formulae for each face2Sum the areas to give the total surface area3
8Square PyramidFind the surface area of this figure with square base 10 cm and height 12 cm.125RT10Use Pythagoras’ theorem to find the height of the triangular face.131013TRPEach triangular face will have base 10 cm and height 13 cm.Hence, total surface area4 triangular faces with the same dimensions and 1 square face12We need to find the height of each triangular face.
9First find the unknown heights using Pythagoras’ theorem Rectangular PyramidFind the surface area of this figure with dimensions as marked.10 cmPQ12 cm8 cmRSTV5 faces altogether:2 pairs of congruent triangular faces1 rectangular faceFirst find the unknown heights using Pythagoras’ theorem588912Hence, total surface area6810
10Cylinder h Hence, total surface area Find the surface area of this cylinder with height 25 cm and diameter 20 cm.Required formula:h25 cmCurved surfaceThink of the net of the cylinder to understand the formula.20Hence, total surface area
11Cone Required formula l refers to the slant height Find the surface area of this cone of height 15 cm radius 5 cm.Required formulal refers to the slant heightlConsider the net of the coneNow calculate the areas.Now sum these areas515lUse Pythagoras’ theoremTotal surface area:
12Sphere Required formula Find the surface area of this sphere with diameter 5 cm.Required formulaEasy! The sphere is one continuous surface so just substitute into the formula
13HemisphereFind the surface area of this hemisphere with diameter 5 cm.Total surface area:A hemisphere is a half sphere. But we need to add in the area of the circular base.Required formula
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