Answer:
a) 3.39 cm b) 21.29 cm
Step-by-step explanation:
ok so the area of a circle is 
r^2.
if the area is 36 cm^2 we can divide it by 3.14, which is pi (). that gives us 11.46. now we find the approximate square root of this. 
this is approximately equal to 3.39. the radius is about 3.39cm.
now that we know the radius, we can easily find the circumference. the formula for this is d. the diameter is just the radius times 2. (3.39)(2)
we plug the numbers into the formula: 3.14(6.78)=21.29 cm =d
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Answer:
x=3
Step-by-step explanation:
2x+3=9
2x=6
x=3
Answer:
36
Step-by-step explanation:
Here is the correct and complete question: The units digit of a two-digit number is twice the tens digit. If the digits are reversed, the new number is 9 less than twice the original number. What is the original number?
Lets assume the original number be"10y+x". (x is unit digit and y is 10th digit)
∴ if number is reversed then resulting number be "10x+y".
As given: x= 2y
and 
Now, solving the equation to get original number.
Distributing 2 to 10y and x, then opening the parenthesis.
⇒ 
subtracting by (2x+y) on both side.
⇒ 
subtituting the value of "x", which is equal to 2y.
∴ 
⇒ 
subtracting both side by (16y-9)
⇒ 
cross multiplying
We get, 
y=3
∵x= 2y
∴ x= 6
Therefore, the original number will be 36 as x is the unit number and y as tenth number.
Answer:
a=10
b=6
Step-by-step explanation:
add 2 to 8, to get a, then subtract 4 from 10 to get b
