Question

4 The door in the diagram is made from a semicircle of radius r and a square with sides of length 2r. The perimeter of the door is 6.4 m long. Find the width of the door in cm.
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Answer 1

Answer:

Given :perimeter =6.4 m

to find :the width of the door in cm

proof :perimeter of a square is 4a sq units

6.4m²=4×a m

a=6.4÷4=1.6 m

therefore the width of the door is 1.6 m in cm 160cm

(and the radiusof the semicircle 160÷2=80cm)