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Deriving formula for area of a trapezium (view source)
Revision as of 11:33, 30 May 2019
, 11:33, 30 May 2019no edit summary
===Learning objectives===
#The trapeium contains two parallel sides and two non-parallel sides.
#The area of trapezium is found by viewing it as a parallelogram.
#The area of trapezium is 1/2(a+b)h where a and b are its parallel sides and h is the perpendicular distance between them.
#The perimeter of a trapezium is obtained by sum of its 4 sides.
===Notes for teachers===
#The area of most figures can be expressed in terms of its dimensions.
#The area of most composite figures can be calculated using the area of primary figures.
===Activity No # 1.Deriving formula for area of a trapezium===
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*Estimated Time: 20 minutes.
*Materials/ Resources needed : Laptop, geogebra file, projector and a pointer.
*Prerequisites/Instructions, if any
#The students should know a parallelogram and formula to find its area.
#They should know the trapezium and its properties.
*Multimedia resources: Laptop
*Website interactives/ links/ / Geogebra Applets: This geogebra file has been taken from :www.geogebratbe.org
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*Process:
#The teacher can initially discuss about a trapezium.
#She can then reiterate that formula for area of certain composite figures can be found by converting them into known simple figures.
#Here the trapezium is converted into a parallelogram.
#Area of parallelogram is then deduced.
*Developmental Questions:
#What is a trapezium ?
#Name its two parallel sides.
#What is meant by the height of the trapezium ?
#After cutting the trapezium exactly in the centre what would be the new height ?
#What is the length of the new parallelogram formed ?
#What is the formula to find the area of a parallelogram ?
#What is the area of this parallelogram formed from a trapezium ?
*Evaluation:
#Explain the sequence of steps involved in deriving the formula for the area of a trapeium.
*Question Corner:
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#Write down the steps involved in deriving the formula for area of trapezium.