11.2.3 Perimeter and Area, PT3 Practice


Question 9:
In diagram below, ADB is a right-angled triangle and DBFE is a square. C is the midpoint of DB and CH = CD.
Calculate the area, in cm2, of the coloured region.

Solution:
Area of  ABC = 1 2 ×6×8 =24  cm 2 Area of trapezium BCHF = 1 2 ×( 12+6 )×6 =54  cm 2 Area of CDEFH =( 12×12 )54 =14454 =90  cm 2 Area of coloured region =24+90 =114  cm 2


Question 10:
Diagram below shows a rectangle ACDE.

Calculate the area, in cm2, of the coloured region.

Solution:
Using Pythagoras theorem (Refer Form 2 Chapter 6) F E 2 =D F 2 D E 2         = 13 2 12 2         =169144         =25 FE= 25 =5 cm AF=85=3 cm AB=128=4 cm Area of rectangle ACDE =8×12 =96  cm 2 Area of  ABF = 1 2 ×3×4 =6  cm 2 Area of  DEF = 1 2 ×5×12 =30  cm 2 Area of coloured region =96306 =60  cm 2


Question 11:
Diagram below shows a sketch of parallelogram shaped garden, PQRS that consists of flower beds and a playground.

Calculate the area, in m2, of the flower beds.

Solution:
Area flower bed =( 12×14 )( 1 2 ×12×7 ) =16842 =126  m 2



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