Answer:
r = (ab)/(a+b)
Step-by-step explanation:
Consider the attached sketch. The diagram shows base b at the bottom and base a at the top. The height of the trapezoid must be twice the radius. The point where the slant side of the trapezoid is tangent to the inscribed circle divides that slant side into two parts: lengths (a-r) and (b-r). The sum of these lengths is the length of the slant side, which is the hypotenuse of a right triangle with one leg equal to 2r and the other leg equal to (b-a).
Using the Pythagorean theorem, we can write the relation ...
((a-r) +(b-r))^2 = (2r)^2 +(b -a)^2
a^2 +2ab +b^2 -4r(a+b) +4r^2 = 4r^2 +b^2 -2ab +a^2
-4r(a+b) = -4ab . . . . . . . . subtract common terms from both sides, also -2ab
r = ab/(a+b) . . . . . . . . . divide by the coefficient of r
The radius of the inscribed circle in a right trapezoid is r = ab/(a+b).
_____
The graph in the second attachment shows a trapezoid with the radius calculated as above.
Options :
A. The initial number of bacteria is 7.
B. The initial of bacteria decreases at a rate of 93% each day.
C. The number of bacteria increases at a rate of 7% each day.
D. The number of bacteria at the end of one day is 360.
Answer:
C. The number of bacteria increases at a rate of 7% each day.
Step-by-step explanation:
Given the function :
f(x)=360(1.07)^x ; Number of bacteria in sample at the end of x days :
The function above represents an exponential growth function :
With the general form ; Ab^x
Where A = initial amount ;
b = growth rate
x = time
For the function :
A = initial amount of bacteria = 360
b = growth rate = (1 + r) = 1.07
If ; (1 + r) = 1.07 ; we can solve for r to obtain the daily growth rate ;
1 + r = 1.07
r = 1.07 - 1
r = 0.07
r as a percentage ;
0.07 * 100% = 7%
9514 1404 393
Answer:
(x +6)^2 +(y -10)^2 = 225
Step-by-step explanation:
The standard form equation for a circle is ...
(x -h)^2 + (y -k)^2 = r^2
where the center is (h, k) and the radius is r.
The center of a circle is the midpoint of any diameter. The midpoint between two points is the average of their coordinates.
((-15, -2) +(3, 22))/2 = (-15+3, -2+22)/2 = (-6, 10)
The radius can be found using the distance formula, or by simply putting one of the given points in the equation for the circle to see what the constant (r^2) needs to be.
(x -(-6))^2 +(y -10)^2 = (-15-(-6))^2 +(-2-10)^2
(x +6)^2 +(y -10)^2 = 81 +144 = 225
The equation of the circle is ...
(x +6)^2 +(y -10)^2 = 225
Hello from MrBillDoesMath!
Answer:
12/5
Discussion:
Note that 10 is a common denominator of both denominators:
9/5 = (9*2)/(5*2) = 18/10
- ( -6/10) = + (6/10)
So the original problem is equivalent to
18/10 + 6/10 =
(18 +6)/10 =
24/10 =
(2*12)/ (2*5) => cancelling the common factor "2"
12/5 =
2 and 2 fifths =
22/5 (though this looks like (22)/5!)
Thank you,
MrB
