# Thread: Solve for D ( true airspeed )

1. ## Solve for D ( true airspeed )

( i tried to ORIENT it properly but it won't budge )

2. ## Re: Solve for D ( true airspeed )

Originally Posted by diehardmath4
( i tried to ORIENT it properly but it won't budge )

Why can you not fit the whole question into the your photo?
The you can use paint or an equivalent program.

PS You can look a program called CamScanner for apple or android. It is excellent at taking pictures of the type you are using.

3. ## Re: Solve for D ( true airspeed )

That is the whole question. It asks you to isolate for d

4. ## Re: Solve for D ( true airspeed )

Originally Posted by diehardmath4
That is the whole question. It asks you to isolate for d
Look, you either do not know how to take a good image or you do not want to try. Which is it?

This is a free service. the least you can do is post readable images.

5. ## Re: Solve for D ( true airspeed )

What you have is $T= I\sqrt{\frac{s}{d}}$. (And you want to solve for "d", not "D".)

You need to "undo" what has been done to d. If you were given values for I, s, and d, to find T you would
1) divide s by d.
2) take the square root.
3) multiply by I

To "undo" that, do the opposite of each step in the reverse order.

The reverse of "multiply by I" is to divide by I. Divide both sides by I to get
$\frac{T}{I}= \sqrt{\frac{s}{d}}$

The reverse of "take the square root" is to square. Square both sides to get
$\frac{T^2}{I^2}= \frac{s}{d}$.

The reverse of "divide by d" is to multiply by d. Multiply both sides by d to get
$\frac{dT^2}{I^2}= s$.

Since it is d we want to solve for, not s, divide both sides by $\frac{T^2}{I^2}$, which, of course, is the same as multiplying both sides by $\frac{I^2}{T^2}$ to get
$d= \frac{sI^2}{T^2}$