To find the answer, use
, and then use the equation
To find it's half life.
Answer:

Step-by-step explanation:
The circumference of a circle with radius
is given by
. The length of an arc is makes up part of this circumference, and is directly proportion to the central angle of the arc. Since there are 360 degrees in a circle, the length of an arc with central angle
is equal to
.
Formulas at a glance:
- Circumference of a circle with radius
:
- Length of an arc with central angle
: 
<u>Question 1:</u>
The radius of the circle is 12 m. Therefore, the circumference is:
The measure of the central angle of the bolded arc is 270 degrees. Therefore, the measure of the bolded arc is equal to:

<u>Question 2:</u>
In the circle shown, the radius is marked as 2 miles. Substituting
into our circumference formula, we get:

The measure of the central angle of the bolded arc is 135 degrees. Its length must then be:

The same way you divide normal numbers, 0.5/0.5 = 1
Answer:
.
Step-by-step explanation:
3x - y = 17 .......A
10 × [x/5 + y/2] = 10 × 0
2x + 5y = 0 .......B
......A× 5 both 2 sides of equation
15x - 5y = 85 .....C
......B + ........C
2x + 15x = 0 + 85
17x = 85
x = 85/17
x = 5
put x value in ........A or .......B or ......C
you will receive y = -2