Step-by-step explanation:
the solution is in the picture
<span>The two checkpoints are 4,920 ft. apart from each other. The total distance of the race is 15,840 ft. If checkpoint C half the distance between checkpoint B and the end of the race, the distance between Checkpoint B and the end of the race is 9,840 ft. Half of that distance is 4,920 ft.</span>
I'm going to assume that the ' 7.51 ' is the angle expressed in radians.
So this is just like any other unit conversion exercise.
You know that 180 degrees = pi radians.
Divide each side by pi radians, and you have
180 degrees / pi radians = 1 .
Great ! Now take the angle you have ... 7.51 radians ...
and multiply it by ' 1 '.
(7.51 radians) x (180 degrees / pi radians) =
<em> </em> (7.51 x 180 / pi) degrees =<em> 430.29 degrees</em>
As you ( I ) worked through this problem, a very useful number
fell out . . . It's 180/pi = 57.296 , or just <em>57.3</em> is close enough.
Here's how you can use that number:
-- 1 radian = <u>57.3</u> degrees
-- 1 degree = 1/57.3 of a radian
-- Got some radians ? Multiply by <u>57.3</u> to get degrees.
-- Got some degrees ? Divide by <u>57.3</u> to get radians.
The function, as presented here, is ambiguous in terms of what's being deivded by what. For the sake of example, I will assume that you meant
3x+5a
<span> f(x)= ------------
</span> x^2-a^2
You are saying that the derivative of this function is 0 when x=12. Let's differentiate f(x) with respect to x and then let x = 12:
(x^2-a^2)(3) -(3x+5a)(2x)
f '(x) = ------------------------------------- = 0 when x = 12
[x^2-a^2]^2
(144-a^2)(3) - (36+5a)(24)
------------------------------------ = 0
[ ]^2
Simplifying,
(144-a^2) - 8(36+5a) = 0
144 - a^2 - 288 - 40a = 0
This can be rewritten as a quadratic in standard form:
-a^2 - 40a - 144 = 0, or a^2 + 40a + 144 = 0.
Solve for a by completing the square:
a^2 + 40a + 20^2 - 20^2 + 144 = 0
(a+20)^2 = 400 - 144 = 156
Then a+20 = sqrt[6(26)] = sqrt[6(2)(13)] = 4(3)(13)= 2sqrt(39)
Finally, a = -20 plus or minus 2sqrt(39)
You must check both answers by subst. into the original equation. Only if the result(s) is(are) true is your solution (value of a) correct.
