If a:b=3:5, find the value of $\displaystyle \dfrac{a}{\sqrt{b^2-a^2}}$
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Originally Posted by requal If a:b=3:5, find the value of $\displaystyle \dfrac{a}{\sqrt{b^2-a^2}}$ note that we have $\displaystyle \frac ab = \frac 35$, that is, $\displaystyle a = \frac 35b$ replace $\displaystyle a$ with this expression in $\displaystyle \frac a{\sqrt{b^2 - a^2}}$ and simplify
i dont think that works as (3/5b)^2 is larger than b^2 thus creating a negative number under a square root?
Originally Posted by requal i dont think that works as (3/5b)^2 is larger than b^2 thus creating a negative number under a square root? 1 - 9/25 is positive. so you have 1b^2 - (9/25)b^2 = (16/25)b^2. how is this negative?
yep, sorry I had mental diaharea thanks anyway
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