1) The side of a square field is 50 m. It is planted with flowers, leaving a margin of 1 m wide all round.Find the area of the margin.
2)Find the area of a circle with circumference 37.68 cm.
3)An aeroplane flies at an average speed of 950km/h from P to Q and back. P and Q are 1140 km apart. Find the flying time.
幫忙列式計算
2007-07-31 9:11 pm
回答 (3)
2007-07-31 9:18 pm
✔ 最佳答案
1.Area of the margin= [ (50 + 1 + 1)^2 - 50^2 ] m^2
= 204 m^2
2.Radius
=Circumference / (2丌)
= 37.68 / (2丌) cm
( I believe the question asks you to take 丌 = 3.14)
= 6 cm
Area
= (6 x 6 x 丌 )cm^2
= 113.10 cm^2 (corr. to 2 d.p.) ---------- for exact value
or = 113.04 cm^2 ---------------- for taking 丌 = 3.14
3. Flying Time
= Average speed / Distance travelled
= (950 km/h) / 1140km
= 5/6 hour
2007-08-02 8:43 pm
good
2007-07-31 9:31 pm
1) Ans = 50^2 - (50-1-1)^2 = 196
2) Circumference = 2兀r , Area = 兀(r^2)
Ans = 兀*(37.68/2兀)^2 = 113.04
3) Ans = 1140*2/950 = 2.4
2) Circumference = 2兀r , Area = 兀(r^2)
Ans = 兀*(37.68/2兀)^2 = 113.04
3) Ans = 1140*2/950 = 2.4
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