p.6升中一maths~~HELP!!!!

2010-08-09 8:31 pm
1)Take Pie equals 22 over 7.Find the area of:
a)a square with perimeter 60 cm
b)a triangle with base 5 cm and height 6 cm
c)a square with side 13mm
d)a rectangle with side 15cm and perimeter 50 cm
e)a trapezium with upper base 3cm, lower base 2cm and height 8cm
f)a right-angled triangle with sides 6 cm, 8cm and 10cm

2)An ice sphere of volume 5832 cm3 is melted and made into a cube. What's the length of the cube?
3)A swimming pool with length 50m and width 25m was filled with 2500 m3 water. Suddenly, a giant comes and drinks half of water ! What's the depth of water now??
4) City A and City B are 120 km apart. A man drives from city A to city B at 40 km/h and returns at 60 km/h. How long do the two journeys together take??
更新1:

sorry Pie should be Pi as u said

回答 (2)

2010-08-10 5:39 am
✔ 最佳答案
1)Take Pie equals 22 over 7.Find the area of:

a)a square with perimeter 60 cm
side of square = 60 cm/4 = 15 cm
Area of square = l side x length = 15 cm x 15 cm = 225 cm^2

b)a triangle with base 5 cm and height 6 cm
area of triangle = base x height / 2 = 5 cm x 6 cm /2 = 15 cm^2

c)a square with side 13mm
Area of square = length of side x length of side = 13 mm x 13 mm = 169 mm^2

d)a rectangle with side 15cm and perimeter 50 cm
length of rectangle = (perimeter – 2x width )/2 = 50 cm – 2 x 15 cm)/2 = 10 cm
area of rectangle = width x length = 15 cm x 10 cm = 150 cm^2

e)a trapezium with upper base 3cm, lower base 2cm and height 8cm
area of trapezium = (upper base + lower base) x height /2
= (3 + 2) x 8 cm/2 = 20 cm^2

f)a right-angled triangle with sides 6 cm, 8cm and 10cm
The hypotenuse of the triangle = 10 cm
Area of triangle = base x height /2 = 6 cm x 8 cm /2 = 24 cm^2
(Pythagorean theorem, 6^2 + 8 cm^2 = 10 cm^2)
The side 6 cm is perpendicular to side 8 cm
The hypotenuse does not come into calculation of area of triangle in this case)
Of course, one can use Heron formula to calculate area of triangle if the length of 3 sides are known for any type of triangle.

2)
Volume of a cube = length of side^3
Length of side = cubic root of volume = cubic root of 5832 cm^3 = 18 cm

3)
Volume of water a giant drinks = (2500 m^3) /2 = 1250 m^3
Volume of water = length x width x depth = 50 cm x 25 cm x depth
1250 m^3 = 50 m x 25 m x depth
depth = 1250 m^3 /(50 m x 25 m) = 1 m

4)
time = distance /speed

time required to travel from City A to City B = 120 km/40 km/h = 3h
time required to travel from City B to City A = 120 km/60 km/h = 2h

All together, the two journeys require = 3h + 2 h = 5 hours

Comment:
PIE means pi = 22/7 = 3.14159…. a constant in maths..

2010-08-10 06:29:57 補充:
回答者:涼
問題 (1) 完全不需要圖,你是否誤解 PIE 這字
所以希望有圖. 這個字 PIE = PI = 22/7 = 3.14159
2010-08-09 10:00 pm
1、p.s.>> / = 除號
a)60/4x15=225 cm2
b)5x6/2=15 cm2
c)13x13=169 mm2
d)[50-(15x2)]/2x15=150 cm2
e)(2+3)x8/2=20 cm2

其實你本作業係咪有圖?因為第一題呢句[1)Take Pie equals 22 over 7.]如果無圖既話其實無意義,如果單純係文字可能以上答案先適用,你自己判斷啦~

另外f)果題其實應該要睇圖來計,因為你要計right-angled triangle既面積應該用連成直角既兩條邊相乘再除二,不過如果真係無圖既話就應該係6x8/2=24 cm2,因為斜邊通常比較長,所以(10)應該不是連成直角既其中一條邊~

2、18cm,18x18x18=5832 cm3
3、2500/25/50/2=1 m
4、120/40+120/60=5 hours
參考: Me


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