1) The scale of a map is 1: 20 000. If two buildings are 3.8 cm apart on the map, then the actual distance between the two buildings is...
2) The scale of a map is 1: 4 000. If the actual area of a sport field is 8 000 m, find its area on the map.
3) OAB is a sector of radius 2 cm. If the arc length of AB is 3πcm, then the area of sector OAB is...
maths questions...........................10points
2008-08-26 1:28 am
回答 (2)
2008-08-26 2:22 am
✔ 最佳答案
Q1.Scale is 1: 20,000. That is 1 cm : 20,000 cm or 1 cm : 200 m.
Therefore, actual distance = 3.8 x 200 m = 760 m.
Q2.
Scale is 1: 4,000, that is 1 cm : 4,000 cm, or 1 cm : 40 m.
Therefore, 1 cm^2 : 40 x 40 m^2, that is 1 cm^2 : 1600 m^2.
Now actual area is 8,000 m^2, therefore, area on map = 8,000/1600 cm^2 = 5 cm^2.
Q3.
Let angle of sector = B. Therefore,
3(pi) = 2(pi)(2) x B/360. So B/360 = 3/4...............(1)
Let area of sector = A, therefore,
A = (pi)(2^2) x B/360 = (pi) x 4 x 3/4 = 3(pi) cm^2.
2008-08-26 2:19 am
1)3.8cm*200000
=760000cm
=7.6km
2)8000m/4000
=2cm
3)2cm*3πcm
=18.84cm sq
=760000cm
=7.6km
2)8000m/4000
=2cm
3)2cm*3πcm
=18.84cm sq
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