2(3.14)r=(3.14)d=circumference of a circle
So...
(3.14)d=56.52
d=56.52/3.14
Diameter=18 cm
Radius=D/2
Radius=18/2
Radius=9 cm
Hope I didn't mess up for your sake.
<span>The half-life of helium-5 is 7.6 × 10^{-22} seconds, and the half-life of helium-9 is 7 × 10^{-21} seconds.
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Approximately

the half-life of helium-9 is greater <span>than that of helium-5.</span>
Answer: 9 times.
Answer: x=1
Step-by-step explanation:
Subtract 1 to both sides leaving you with x=1
Answer:
The numbers are 91 and 81
Step-by-step explanation:
Let:
x be the first number.
y be the second number.
The sum of two numbers is 172.
x + y = 172
Their difference is 10.
x - y = 10
Try to arrange for solving x:
x - y = 10
x = 10 + y
Now substitute the x to the first equation.
x + y = 172
(10 + y) + y = 172
10 + y + y = 172
10 + 2y = 172
2y = 172 - 10
2y = 162
y = 162 ÷ 2
y = 81
Now solve for x:
x + y = 172
x + (81) = 172
x = 172 - 81
x = 91
Now let's check one more time:
The sum of two numbers is 172:
91 + 81 = 172
172 = 172 (correct)
Their difference is 10:
91 - 81 = 10
10 = 10 (correct)