# Math Help - Rewriting Formula

1. ## Rewriting Formula

Hello forum, Vairon here.
I'm having trouble rewriting any kind of formula but I can hopefully understand the first one and use it as reference.

Solve for r
$C&=2&\pi&r$
I assume
C/2r*pi should solve it

2. ## Re: Rewriting Formula

Not exactly. If you divide both sides by $2 \pi r$, you get "1" on the right hand side, not r!

So just divide by $2 \pi$ to get $r = \frac{C}{2 \pi}$

3. ## Re: Rewriting Formula

Originally Posted by TheChaz
Not exactly. If you divide both sides by $2 \pi r$, you get "1" on the right hand side, not r!

So just divide by $2 \pi$ to get $r = \frac{C}{2 \pi}$
I feel proud I actually got it before the response thanks though btw just to know I'm doing everything right I got this one answered.

Area of a triagle
Solve for b : $A&=\frac{1}{2}&bh$

I solved it : $\frac{A}{\frac{1}{2}*h}&=b$

4. ## Re: Rewriting Formula

$b = \frac{2A}{h}$

5. ## Re: Rewriting Formula

Originally Posted by skeeter
$b = \frac{2A}{h}$
Will mine work?
I tried plugin in the numbers and both formulas output the same number

6. ## Re: Rewriting Formula

Originally Posted by vaironxxrd
Will mine work?
I tried plugin in the numbers and both formulas output the same number
it'll work, but you're expected to be able to clear any fraction "inside" another fraction.

7. ## Re: Rewriting Formula

Originally Posted by skeeter
it'll work, but you're expected to be able to clear any fraction "inside" another fraction.
I'm sorry to ask this but why is it 2?

Flip and multiply?

8. ## Re: Rewriting Formula

Originally Posted by vaironxxrd
I'm sorry to ask this but why is it 2?

Flip and multiply?
Roughly speaking, yes.

9. ## Re: Rewriting Formula

Originally Posted by vaironxxrd
I feel proud I actually got it before the response thanks though btw just to know I'm doing everything right I got this one answered.

Area of a triagle
Solve for b : $A&=\frac{1}{2}&bh$

I solved it : $\frac{A}{\frac{1}{2}*h}&=b$

\displaystyle \begin{align*} A &= \frac{1}{2}bh \\ 2A &= 2\cdot \frac{1}{2}bh \\ 2A &= bh \\ \frac{2A}{h} &= \frac{bh}{h} \\ \frac{2A}{h} &= b \end{align*}

10. ## Re: Rewriting Formula

Originally Posted by vaironxxrd
Solve for b : $A&=\frac{1}{2}&bh$
or start off by multiplying both sides by 2:
2A = bh ; then:
b = 2A / h
Done.