+97 Differentiated Equation:
dA/dr=(2*(pi^2*r^6-64800)/(r^2sqrt(pi^2*r^6+129600)))
Let dA/dr=0
Therefore: 0=(2*(pi^2*r^6-64800)/(r^2sqrt(pi^2*r^6+129600)))
Find 'r', with working, please :)?
NOTE: In the original question, the 'r' value will represent the radius in the volume formula of a cone. Resulting in finding 'h' value of the formula.
Known infomation of the volume formula:
V=120ml
so, 120=1/3 pi*r^2*h
Thanks again, ask any questions if it is not clear.
+33652 For your expression to be zero you must have the term in brackets in the numerator to be zero; so:
pi2*r6 - 64800 = 0 or r = 648001/6/pi1/3
$${\mathtt{r}} = {\frac{{{\mathtt{64\,800}}}^{\left({\frac{{\mathtt{1}}}{{\mathtt{6}}}}\right)}}{{{\mathtt{\pi}}}^{\left({\frac{{\mathtt{1}}}{{\mathtt{3}}}}\right)}}} \Rightarrow {\mathtt{r}} = {\mathtt{4.327\: \!255\: \!548\: \!039\: \!541\: \!4}}$$
+33652 For your expression to be zero you must have the term in brackets in the numerator to be zero; so:
pi2*r6 - 64800 = 0 or r = 648001/6/pi1/3
$${\mathtt{r}} = {\frac{{{\mathtt{64\,800}}}^{\left({\frac{{\mathtt{1}}}{{\mathtt{6}}}}\right)}}{{{\mathtt{\pi}}}^{\left({\frac{{\mathtt{1}}}{{\mathtt{3}}}}\right)}}} \Rightarrow {\mathtt{r}} = {\mathtt{4.327\: \!255\: \!548\: \!039\: \!541\: \!4}}$$
