The surface area A of a sphere is given by the formula A =4兀r^2
where r is the radius of the sphere
a) Find the value of A hwen
i) 兀=3.14 and r=1
ii) 兀=22/7 and r=3.5
b)Make r^2 the subject of the formula
c) Find the value of r for each of the following values of A
i) 36兀
ii) 196兀
*I want clear steps . Thanks a lot .
Who is the the best i will give (10x2=20marks)
F.2 Maths (in hurry!)Thanks a lot!
2006-10-18 5:59 am
回答 (3)
2006-10-18 6:13 am
✔ 最佳答案
a1) Area=4 X 3.14 X 1X1=12.56a2)Area=4 X 22/7 X 3.5 X 3.5=154
b) A=4兀r^2
r^2=A/4兀
c1) r^2=A/4兀
Now A=36兀 , So r^2=36兀/4兀
r^2=9
r=3
c2) r^2=A/4兀
Now A=196兀 , So r^2=196兀/4兀
r^2=49
r=7
2006-10-18 6:16 pm
a)
i) A = 4(3.14)1^2 = 25.12
ii) A = 4(22/7)(3.5)^2 = 157
b) A =4兀r^2
r^2 = 4兀/A
c)
i) A =36兀
4兀r^2 = 36兀
r^2 = 9
r = 3
ii) A = 196兀
4兀r^2 = 196兀
r^2 = 49
r = 7
i) A = 4(3.14)1^2 = 25.12
ii) A = 4(22/7)(3.5)^2 = 157
b) A =4兀r^2
r^2 = 4兀/A
c)
i) A =36兀
4兀r^2 = 36兀
r^2 = 9
r = 3
ii) A = 196兀
4兀r^2 = 196兀
r^2 = 49
r = 7
2006-10-18 6:18 am
ai) A= 4(3.14)(1^2)
= 12.56
aii) A= 4(22/7)(3.5^2) or A= 4(22/7)(3.5^2)
= 88/7 x 12.25 = (22/7)(7^2)
= 154 = 22 x 7
= 154
b) A = 4兀r^2
A/4兀= (4兀r^2)/4兀
r^2= A/4兀
ci) r^2=36兀/4兀
r^2=9
r=3
cii) r^2=196兀/4兀
r^2=49
r=7
2006-10-17 22:20:31 補充：
sorry for the question (aii)it isA= 4(22/7)(3.5^2)= 88/7 x 12.25 = 154 orA= 4(22/7)(3.5^2)= (22/7)(7^2)= 22 x 7= 154
= 12.56
aii) A= 4(22/7)(3.5^2) or A= 4(22/7)(3.5^2)
= 88/7 x 12.25 = (22/7)(7^2)
= 154 = 22 x 7
= 154
b) A = 4兀r^2
A/4兀= (4兀r^2)/4兀
r^2= A/4兀
ci) r^2=36兀/4兀
r^2=9
r=3
cii) r^2=196兀/4兀
r^2=49
r=7
2006-10-17 22:20:31 補充：
sorry for the question (aii)it isA= 4(22/7)(3.5^2)= 88/7 x 12.25 = 154 orA= 4(22/7)(3.5^2)= (22/7)(7^2)= 22 x 7= 154
收錄日期: 2021-04-12 22:40:57
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